JPH11213268A - Alarm transfer device and method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce an alarm area in a transmission line by using the priority of an alarm, and to secure a sufficient transmission area of a main signal. SOLUTION: Alarm information A1-An is transmitted from a remote device in response to the generation of an alarm, and the alarm information A1-An transmitted in parallel is stored in each area of a memory part 11. The alarm information A1-An is successively read in accordance with its priority by a priority processing part 12, and coded also in accordance with its priority by a code converting part 13 in the next stage. A code C obtained as a result is mapped to a transmission line signal, and transferred by a transferring part 14.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an alarm transfer device and an alarm transfer method for transferring, for example, alarm information monitored by a remote device.

[0002]

2. Description of the Related Art FIG. 13 is a block diagram showing a conventional alarm transfer device. In FIG. 13, reference numeral 4 denotes an alarm transfer device, and reference numeral 41 denotes a time division multiplexing unit provided in the alarm transfer device 4. is there. A1 to An (n is a natural number) are alarm information for each monitoring item sent from a remote device (not shown).

Next, the operation will be described. FIG. 14 is a diagram for explaining a frame of an alarm item according to a conventional example.
To the alarm transfer device shown in FIG. 13, n pieces of alarm information A1 to An are sent from the remote device. These alarm information A
1 to An represent status bits (“1”: generated, “0”: not generated) for each of the n monitoring items.
In the time division multiplexing section 41, these pieces of alarm information A1 to An are time division multiplexed, and a multiplexed signal B having the frame format shown in FIG. 14 is obtained. Then, the multiplexed signal B is transmitted (transferred).

As an approximation technique, there is, for example, JP-A-246554. This publication discloses a technique of assigning a special code to a state change generated in a monitored device and collecting state change information using the special code in order to reduce the amount of information and shorten the time for collecting information. It has been disclosed.

[0005]

Since the conventional alarm transfer device is configured as described above, it is necessary to expand the alarm area in the transmission path signal with the increase in the number of alarm items monitored by the remote device. . That is, since the multiplexed signal B is information transferred every frame, the larger the number n indicating the number of alarm items is, the larger the information amount of the multiplexed signal B is and the smaller the transmission area of the main signal is. There was a point.

Further, focusing on the reliability of the apparatus, in order to further enhance the reliability, the pilot pattern and the CR
A new bit area for providing a C check bit or the like is required. Since this new bit area is provided in the transmission area of the main signal, there is a problem that the transmission area of the main signal is reduced.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and reduces the alarm area on a transmission line by utilizing the priority of alarms, thereby ensuring a sufficient main signal transmission area. It is another object of the present invention to provide an alarm transfer device and an alarm transfer method capable of preventing the reduction of the transmission area of the main signal and improving the reliability of the device.

[0008]

Means for Solving the Problems The above-mentioned problems are solved,
To achieve the first object, an alarm transfer device according to the present invention is an alarm transfer device that performs alarm transfer by assigning an alarm signal to a transmission line signal transmitted to a transmission line. Storage means for storing alarm information of the following, priority processing means for reading out only alarms whose status has changed in accordance with a predetermined priority, and read out by the priority processing means. Code conversion means for converting alarm information into a predetermined code, and transfer means for transferring by assigning the alarm information coded by the code conversion means to the transmission path signal. .

According to the present invention, a plurality of pieces of alarm information are converted into a predetermined code after priority processing and transferred after utilizing the priority of alarms, so that the alarm information occupies the transmission line. The bit area is reduced, so that a sufficient transmission area for the main signal can be secured.

According to another aspect of the present invention, there is provided an alarm transfer device for generating a monitoring pattern for monitoring a transmission path when there is no change in the state of an alarm, and for generating a coded pattern for the transmission path signal. Insertion means for inserting the monitoring pattern generated by the generation means into an area to which alarm information is to be assigned.

According to the present invention, when there is no change in the alarm status, a plurality of alarms are converted into a predetermined code after priority processing and then transferred, and a monitoring pattern such as a pilot pattern is stored in the alarm transfer area. Is inserted, so that the alarm area when there is no change in the alarm state is effectively used in monitoring the transmission path. This allows
The transmission quality, that is, the reliability of the device can be improved without reducing the bit area occupied by the main signal in the transmission path.

According to another aspect of the present invention, there is provided an alarm transfer device for generating a CRC check bit when there is no change in the state of an alarm, and in a region where the coded alarm information is to be assigned to the transmission path signal. Inserting means for inserting the CRC check bit generated by the generating means;
Is further provided.

According to the present invention, when there is no change in the alarm status, a plurality of alarms are coded and transferred after priority processing, and the CRC check bit of the control signal is inserted into the alarm transfer area. In addition, the alarm area when there is no change in the alarm state is effectively used in terms of the reliability of the information transferred. This makes it possible to improve the transmission quality, that is, the reliability of the device, without reducing the bit area occupied by the main signal in the transmission path.

An alarm transfer method according to the next invention is an alarm transfer method for performing alarm transfer by assigning an alarm signal to a transmission path signal transmitted to a transmission path, wherein a plurality of pieces of alarm information input for each alarm item are used. A first step of converting only an alarm whose state has changed into a predetermined code according to a predetermined priority; and a step of transferring the alarm information coded by the first step by assigning the alarm information to the transmission path signal. And two steps.

According to the present invention, the priority of the alarm is used to convert a plurality of pieces of alarm information into a predetermined code after the priority processing, and then to transfer the code. The area is reduced. As a result, it is possible to secure a sufficient transmission area for the main signal.

An alarm transfer method according to the next invention includes a third step of generating a monitoring pattern for monitoring a transmission path when there is no change in the state of an alarm, and a step of generating a monitoring pattern for the transmission path signal when an alarm is generated. And inserting a monitoring pattern generated in the third step into an area to which the coded alarm information is to be assigned.

According to the present invention, when there is no change in the state of the alarm, a plurality of alarms are coded and transferred after priority processing, and a monitoring pattern such as a pilot pattern is inserted into the alarm transfer area. In addition, the alarm area when there is no change in the alarm state is effectively used in monitoring the transmission path. This makes it possible to improve the transmission quality, that is, the reliability of the device, without reducing the bit area occupied by the main signal in the transmission path.

An alarm transfer method according to the next invention is characterized in that a fifth step of generating a CRC check bit when there is no change in the state of the alarm, and that the coded alarm is generated for the transmission path signal when an alarm is generated. And a sixth step of inserting the CRC check bit generated in the fifth step into an area to which information is to be allocated.

According to the present invention, when there is no change in the state of the alarm, a plurality of alarms are coded and transferred after priority processing, and the CRC check bit of the control signal is inserted into the alarm transfer area. In addition, the alarm area when there is no change in the alarm state is effectively used in terms of the reliability of the information transferred. This makes it possible to improve the transmission quality, that is, the reliability of the device, without reducing the bit area occupied by the main signal in the transmission path.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of an alarm transfer device and an alarm transfer method according to the present invention will be described below in detail with reference to the accompanying drawings.

Embodiment 1 First, the configuration will be described. FIG. 1 is a block diagram showing an alarm transfer device according to Embodiment 1 of the present invention. In FIG. 1, reference numeral 1 denotes an alarm transfer device. The alarm transfer device 1 includes, for example, a memory unit 11 for storing alarm information of each alarm item, a priority processing unit 12 for giving priority only to alarm items whose status has changed with respect to the alarm items, and a priority order of the alarm items. It is configured by a code conversion unit 13 and a transfer unit 14 that convert alarm information into a predetermined code and add information indicating a change in the state of the alarm.

Next, the operation will be described. 2 illustrates a frame format of an output code according to the first embodiment, FIG. 3 illustrates a priority of an alarm, FIG. 4 illustrates an example of an output code, and FIG. 6 is a flowchart illustrating an operation according to the first exemplary embodiment.

FIG. 2 shows a status change presence / absence bit S (1 bit) indicating presence / absence of a status change of the alarm and 13 bits in the code conversion unit.
2 shows an output format formed by the code C obtained by the above. Here, the state change presence / absence bit S is
"1" if there is a change in alarm status, "0" otherwise
Becomes

In the following description, as shown in FIG. 3, as an example, there are four types of alarm items (n = 4), and the alarm information is set so that the priority is lowered from A1 to A4. Here, when the number of bits of the code C is represented by m, n =
It has a relationship of 2 ^m . From this, when n = 4,
m = 2. Therefore, the output code based on the state change presence / absence bit S and the code C is composed of three bits, one bit of S and two bits of C, as shown in FIG.

In the alarm transfer device shown in FIG. 1, since alarm information A1 to An is sent from the remote device regarding the state of the alarm, the alarm information A1 to A1 sent in parallel to each area of the memory unit 11 is transmitted. An is stored (step S
1).

The n pieces of alarm information A1 to An stored in the memory unit 11 are sequentially read out from the priority processing unit 12 in the order of higher priority, only the information whose status has changed, and It is transferred (step S2).
The code conversion unit 13 converts the high-priority alarm information into a predetermined code C, and adds a status change presence / absence bit S to the code C (step S3).

As a result, an m (n> m) -bit code C having a smaller number of bits than the conventional n-bit multiplexed signal B is obtained (see FIG. 4). Then, the output code is mapped to a transmission path signal by the transfer unit 14 and transferred to a game (not shown) (step S4).

Further, the case where n = 4 will be described with reference to FIG. FIG. 6 is a diagram illustrating the state transition of the output code that changes according to the state change of the alarm. For example, when alarm status changes occur simultaneously in all of A1 to A4, the output code of the first frame is expressed in binary 10 bits.
0 (B). This output code “100 (B)”
S = 1 (B) and C = 00 (B). At the time of output, since the priority order is followed, a 2-bit code C is generated in the order of A1 to A4 after an alarm state change occurs.

In the subsequent second frame, only code C is A2
01 (B), and only the code C changes to 10 (B) in the subsequent third frame. Then, the alarm information A
If only 1 recovers, A1
Has the highest priority, the code C “00”
(B) "is transferred in advance.
In the frame, the alarm information A4 having the lowest priority
The code C “11 (B)” is transferred.

In this manner, the transfer of the output codes relating to the alarm information A1 to A4 in which the state change has occurred at the same time is completed. Therefore, in the subsequent sixth frame, since there is no state change in each alarm, the state change presence / absence bit S is set to “0”.
(B) ", and the bit portion corresponding to the code C becomes invalid.

Then, when the alarm information A3 is recovered during the transfer of the next seventh frame, a change in the state of the alarm has appeared at that point.
Changes to “1 (B)”. At this time, the information assigned to the code C is information relating to the alarm information A3 having a state change. Therefore, code C is "10
(B) ".

Further, when the alarm information A2 and A4 are simultaneously recovered during the transfer of the next eighth frame, a change in the state of the alarm has also appeared here, so that the state change presence / absence bit S "1" (B) "is held. At this time, the information assigned to the code C is the alarm information A2, A4 having the status change, but also in this case, the information is assigned according to the priority order.
2 is transferred. Accordingly, first, the code C “01 (B)” is transferred in the eighth frame, and the code C “11 (B)” is transferred in the following ninth frame.

In this way, the transfer of the output codes related to the alarm information A2 and A4 in which the state change has occurred at the same time is completed. Therefore, in the subsequent tenth frame, since there is no state change in each alarm, the state change presence / absence bit S changes to “0 (B)”, and the bit portion corresponding to the code C becomes invalid.

As described above, according to the first embodiment, a plurality of pieces of alarm information are converted into a predetermined code after priority processing using the priority of alarms, and then transferred. The bit area occupied by the alarm information in the transmission path is reduced. As a result, a sufficient transmission area for the main signal can be ensured, and the information amount of the main signal can be increased.

Embodiment 2 Further, the present invention is similar to the first embodiment described above, as in the second embodiment described below.
In the above, a bit for allocating a code to be transferred when there is no change in the alarm state may be used effectively.

First, the configuration will be described. FIG. 7 is a block diagram showing an alarm transfer device according to a second embodiment of the present invention. In FIG. 7, reference numeral 2 denotes an alarm transfer device. The alarm transfer device 2 includes, for example, a first alarm processing unit 2
The first and second alarm processing units 22 are provided.

The first alarm processor 21 has the same configuration as the alarm transfer device 1 of the first embodiment as a whole. That is, the alarm processing unit 21 includes, for example, a memory unit 201 that stores alarm information of each alarm item, a priority processing unit 202 that gives priority only to an alarm item whose state has changed with respect to the alarm item, and an alarm item A code conversion unit 20 that converts the alarm information into a predetermined code according to the priority and adds the state change presence / absence bit S described above.
3.

On the other hand, the second alarm processing section 22 generates a monitoring pattern such as a pilot pattern when there is no change in the alarm state, for example. The monitoring pattern insertion unit 205 and the transfer unit 206 perform the transfer.

Next, the operation will be described. FIG. 8 is a diagram for explaining a frame format of an output code in the second embodiment, and FIG. 9 is a flowchart for explaining an operation according to the second embodiment. In the alarm transfer device shown in FIG. 7, when a state change occurs in the alarm (step S11), similar to the first embodiment,
Alarm information A1 to An is sent from the remote device. Therefore, the alarm information A1 to An sent in parallel is stored in each area of the memory unit 201 (step S1).
2).

The n pieces of alarm information A1 to An stored in the memory unit 201 are, in the same manner as in the first embodiment described above, only those whose state has changed in the priority processing unit 202 and whose priority is higher. They are sequentially read out and transferred to the code conversion unit 203 (step S13). In the code conversion unit 203, similarly to the above-described first embodiment, conversion from the high-priority alarm information to a predetermined code is performed, and the state change presence / absence bit S “1” is added (step S14). ).

As a result, as in the first embodiment, an m-bit (n> m) -bit code C having a smaller number of bits than the conventional n-bit multiplexed signal B is obtained (FIG. 8 ( a)). The code C and the status change presence / absence bit S are mapped to a transmission path signal by the transfer unit 206 of the second alarm processing unit 22 and transferred to a game (not shown) (step S15).

On the other hand, when there is no change in the state of the alarm (step S11), the monitoring pattern generation unit 204 generates a monitoring pattern such as a pilot pattern (step S16). Then, the monitoring pattern D generated by the monitoring pattern generation unit 204 is selected in the monitoring pattern insertion unit 205, and the monitoring pattern D is inserted into the transmission path signal instead of the code C (step S17).

It should be noted that even if there is no change in the alarm state, 1
The state change presence / absence bit S (“0”) corresponding to the bits is generated.
05 is added to the monitoring pattern D (FIG. 8B)
reference). The monitoring pattern D and the status change presence / absence bit S are mapped to a transmission path signal by the transfer unit 206 and transferred to the terminal (step S15). At this time, on the playing side, the transfer pattern is set to the value of S and the alarm code C
Or the monitoring pattern D is determined.

As described above, according to the second embodiment, in addition to converting a plurality of alarms into a predetermined code after priority processing and transferring the same, the alarm transfer is performed when there is no change in the state of the alarm. Since the monitoring pattern such as the pilot pattern is inserted into the area, the alarm area when there is no change in the alarm state is effectively used for monitoring between transmission paths. This makes it possible to improve the transmission quality, that is, the reliability of the device, without reducing the bit area occupied by the main signal in the transmission path.

Embodiment 3 Further, the present invention is similar to the above-described first embodiment as in a third embodiment described below.
In a different application from the above-described second embodiment, a bit for allocating a code to be transferred when there is no change in the alarm state may be used effectively. In the third embodiment, the same components as those in the above-described second embodiment are denoted by the same reference numerals, and description thereof will be omitted.

First, the configuration will be described. FIG. 10 is a block diagram showing an alarm transfer device according to a third embodiment of the present invention. In FIG. 10, reference numeral 3 denotes an alarm transfer device. The alarm transfer device 3 includes, for example, a first alarm processing unit 21 (see FIG. 4 of the second embodiment) and a second alarm processing unit 31.

The first alarm processing section 21 is the same as that of the second embodiment, and the description is omitted. The second alarm processing unit 31, for example, outputs a CR such as a control signal when no alarm is generated.
C (Cyclic Redundancy Chec)
k) CRC check bit generating section 301 for generating check bits, CRC check bit inserting section 30 for inserting (transmitting) CRC check bits into transmission path signals
2 and a transfer unit 303.

Next, the operation will be described. FIG. 11 is a diagram for explaining a frame format of an output code in the third embodiment, and FIG.
Is a flowchart for explaining the operation according to the present embodiment. In the alarm transfer device shown in FIG. 10, when a state change occurs in the alarm (step S21), the alarm information A1 to An is sent from the remote device as in the first embodiment.
Therefore, the alarm information A1 to An sent in parallel is stored in each area of the memory unit 201 (step S).
22).

The n pieces of alarm information A1 to An stored in the memory unit 201 are, in the same manner as in the first embodiment, the ones whose status has been changed in the priority processing unit 202 and have the highest priority. They are sequentially read and transferred to the code conversion unit 203 (step S23). The code conversion section 203 converts the high-priority alarm information into a predetermined code, and adds a state change presence / absence bit S “1” (step S24).

As a result, an m-bit (n> m) -bit code C having a smaller number of bits than the conventional n-bit multiplexed signal B is obtained (see FIG. 11A). The code C and the state change presence / absence bit S are mapped to a transmission path signal by the transfer unit 303 of the second alarm processing unit 31 and transferred to a game (not shown) (step S25).

On the other hand, if there is no state change in the alarm (step S21), the CRC check bit generator 30
In step 1, a CRC check bit such as a control signal is generated (step S26). At this time, as in the case of the generation of the monitoring pattern in the above-described second embodiment, the CRC check bit E has one state change presence / absence bit S “0”.
Is added (see FIG. 11B).

Then, the CRC check bit insertion unit 30
In step 1, the CRC check bit E and the state change presence / absence bit S generated by the CRC check bit generation unit 301 are selected, and the CRC check bit E and the state change presence / absence bit S are transmitted instead of the code C and the state change presence / absence bit S. (Step S2)
7). The CRC check bit E and the status change presence / absence bit S are mapped to a transmission path signal by the transfer unit 303 and transferred to the opposite terminal (step S25). At this time, the game side determines whether the transfer pattern is the alarm code C or the CRC check bit E based on the value of S.

As described above, according to the third embodiment, in addition to converting a plurality of alarms into a predetermined code after priority processing and transferring the same, the alarm transfer is performed when there is no alarm state change. Since the CRC check bit of the control signal is inserted in the area, the alarm area when there is no change in the alarm state can be effectively used in terms of the reliability of information transferred. This makes it possible to improve the transmission quality, that is, the reliability of the device, without reducing the bit area occupied by the main signal in the transmission path.

[0054]

As described above, according to the present invention, a plurality of pieces of alarm information are converted into a predetermined code after the priority processing using the priority of the alarm, and then transferred. The bit area occupied by the alarm information in the transmission path is reduced, thereby providing an alarm transfer device capable of sufficiently securing the main signal transmission area.

According to the next invention, when there is no change in the state of the alarm, a plurality of alarms are converted into a predetermined code after priority processing and then transferred, and a pilot pattern or the like is monitored in the alarm transfer area. Since the pattern is inserted, the alarm area when there is no change in the alarm state is effectively used for monitoring between transmission paths.
There is an effect that an alarm transfer device capable of improving the transmission quality, that is, the reliability of the device, without reducing the bit area occupied by the main signal in the transmission path is obtained.

According to the next invention, when there is no change in the state of the alarm, a plurality of alarms are converted into a predetermined code after priority processing and then transferred, and the CRC of the control signal is checked in the alarm transfer area. Since the bit is inserted, the alarm area when there is no change in the alarm state is effectively used in terms of the reliability of the transferred information.
There is an effect that an alarm transfer device capable of improving the transmission quality, that is, the reliability of the device, without reducing the bit area occupied by the main signal in the transmission path is obtained.

According to the next invention, the process of converting a plurality of pieces of alarm information into a predetermined code after priority processing using the priority of alarms and transferring the same is performed, so that the alarm information occupies the transmission line. The bit area is reduced, thereby providing an effect that an alarm transfer method capable of sufficiently securing a main signal transmission area is obtained.

According to the next invention, when there is no change in the state of the alarm, a plurality of alarms are converted into a predetermined code after priority processing and then transferred, and a pilot pattern or the like is monitored in the alarm transfer area. Since the process of inserting the pattern is used, the alarm area when there is no change in the state of the alarm is effectively utilized in terms of monitoring between transmission paths.
There is an effect that an alarm transfer method capable of improving the transmission quality, that is, the reliability of the device, without reducing the bit area occupied by the main signal in the transmission path is obtained.

According to the next invention, when there is no change in the state of the alarm, a plurality of alarms are converted into a predetermined code after priority processing and then transferred, and a CRC check of the control signal is performed in the alarm transfer area. Since the bit is inserted, the alarm area when there is no change in the alarm state is effectively used in terms of the reliability of the transferred information.
There is an effect that an alarm transfer method capable of improving the transmission quality, that is, the reliability of the device, without reducing the bit area occupied by the main signal in the transmission path is obtained.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an alarm transfer device according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating a frame format of an output code according to the first embodiment.

FIG. 3 is a diagram illustrating the priority order of alarms according to the first embodiment.

FIG. 4 is a diagram showing an example of an output code according to the first embodiment.

FIG. 5 is a flowchart illustrating an operation according to the first embodiment.

FIG. 6 is a diagram illustrating a state transition of an output code that changes according to a state change of a report according to the first embodiment.

FIG. 7 is a block diagram showing an alarm transfer device according to a second embodiment of the present invention.

FIG. 8 is a diagram illustrating a frame format of an output code according to the second embodiment.

FIG. 9 is a flowchart illustrating an operation according to the second embodiment.

FIG. 10 is a block diagram showing an alarm transfer device according to a third embodiment of the present invention.

FIG. 11 is a diagram illustrating a frame format of an output code according to the third embodiment.

FIG. 12 is a flowchart illustrating an operation according to the third embodiment.

FIG. 13 is a block diagram showing an alarm transfer device according to a conventional example.

FIG. 14 is a diagram illustrating a frame of an alarm item according to a conventional example.

[Explanation of symbols]

1,2,3 alarm transfer device, 11,201 memory unit,
12, 202 priority processing unit, 13, 203 code conversion unit, 14, 206, 303 transfer unit, 21 first alarm processing unit, 22, 31 second alarm processing unit, 204 monitoring pattern generation unit, 205 monitoring pattern insertion unit, 301 C
RC check bit generation unit, 302 CRC check bit insertion unit.

Claims (6)

[Claims] 1. An alarm transfer device for performing alarm transfer by assigning an alarm signal to a transmission line signal transmitted to a transmission line, wherein only an alarm whose state has changed is stored based on a plurality of pieces of alarm information input for each alarm item. Storage means for performing the following: priority processing means for reading alarm information stored in the storage means in accordance with a predetermined priority; code conversion for converting the alarm information read by the priority processing means into a predetermined code. Means for transferring alarm information coded by the code converting means to the transmission path signal by transferring the alarm information. 2. A generating means for generating a monitoring pattern for monitoring a transmission path when there is no alarm state change, and wherein the coded alarm information is assigned to an area to which the coded alarm information is to be assigned to the transmission path signal. The alarm transfer device according to claim 1, further comprising: an insertion unit that inserts the monitoring pattern generated by the generation unit. 3. A generating means for generating a CRC check bit when there is no alarm state change, and a C signal generated by said generating means in an area to which said coded alarm information is to be assigned to said transmission path signal.
The alarm transfer device according to claim 1, further comprising: an insertion unit that inserts an RC check bit. 4. An alarm transfer method for performing an alarm transfer by assigning an alarm signal to a transmission path signal transmitted to a transmission path, wherein only a warning whose state has changed is previously determined based on a plurality of pieces of alarm information input for each alarm item. A first step of converting to a predetermined code according to a predetermined priority; and a second step of transferring the alarm information coded by the first step by assigning the alarm information to the transmission path signal. A method of transmitting information. 5. A third step of generating a monitoring pattern for monitoring a transmission path when there is no change in the state of an alarm, and the coded alarm information for the transmission path signal when an alarm is generated. The alarm transfer method according to claim 4, further comprising: a fourth step of inserting the monitoring pattern generated in the third step into an area to which is assigned. 6. A fifth step of generating a CRC check bit when there is no change in the state of the alarm, and in a region where the coded alarm information is to be assigned to the transmission path signal when an alarm is generated. The method of claim 4, further comprising: inserting a CRC check bit generated in the fifth step.