JPH03240337A - Serial communication system - Google Patents

Abstract

PURPOSE:To avoid mis-setting and malfunction by easily setting a slave station from a master station and eliminating the need for an address setting switch for the slave station. CONSTITUTION:A master station 1 is provided with line drivers 51-53 and lien receivers 61-63 corresponding to slave stations and each line driver/receiver is enabled/disabled for each slave station and it is controlled by a PAL 4. Moreover, each of slave stations 21-23 is provided with a memory (71-73) able to store an address. After the reset, the master station enables the line driver in the 1st communication after the normal end of check of a ROM and a RAM or the like for each slave station, communicates address information specific to each slave station and the slave station uses a storage means to store the received address information. Thus, the master station easily sets an address and no address setting switch is required for the slave station and mis-setting and malfunction are avoided.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an address setting method for serial communications consisting of one master station and a plurality of slave stations.

[Prior Art] Conventionally, in a serial communication network having a plurality of slave stations, address information for distinguishing each slave station is set using a jumper, short switch, rotary inch, etc. provided in the slave station, or It had a built-in ROM that recorded address information.

Furthermore, in JP-A No. 62-173836, an ID code is set using multiple switches installed in the CA and TV terminal, and if the ID code does not match the ID code held in the E2P-ROM installed in the CATV, the center Do not send to.

[Invention tries to solve &! Title]

In the first conventional example described above, if a jumper, short switch, rotary switch, etc. is set to the wrong address either intentionally or by mishandling, and there is a slave station with the same address, the The disadvantage is that the master station cannot receive information from the slave station.

Furthermore, the second conventional example has the disadvantage that the ROM must be changed every time the address of a slave station is changed, and ROMs with different contents must be prepared for each slave station.

On the other hand, in the method of Jikai 62-173836, the above E"
Even if an ID code is incorrectly set in the P-ROM, if the switch is set to be the same as the ID code in the E'' P-ROM, the data will be sent to the center.

[Means for Solving the Problems] In order to solve the above problems, the present invention connects the master station and each slave station with individual lines, and connects the line driver/line receiver on the master station side to each slave station. It is equipped with a means for enabling/disabling each slave station, a means for simultaneously enabling the above-mentioned line drivers, and a means for storing its own address information on the slave station side. The slave station is enabled for each slave station to communicate unique address information to the slave station, and the slave station stores the received address information using the storage means.

[Effect]

By means of the above means, the address can be easily set from the master station, and no switch for address setting is required in the slave station, thereby eliminating erroneous settings and erroneous operations.

(Embodiment) FIG. 1 shows a block diagram showing a circuit configuration in an embodiment of the present invention.

In addition, a flowchart showing the operation explanation is shown in Fig. 2.
FIG. 3 shows an explanation of the PAL operation, and FIG. 4 shows an explanation of the operation of PAL.

The master station 1 of this embodiment has line drivers (51 to 53) (for example, MC3487 from Ti) for each slave station.
, line receivers (61 to 63) [for example, Ti company's MC
3486), and each line driver/receiver can be individually enabled/disabled, and the circuit for controlling them can be easily implemented with PAL4 (for example, AMD's PALL6L8A).

On the other hand, the slave stations 21-23 have memories 71-73 that can store addresses.

After the reset master station successfully completes various self-checks (for example, ROM check, RAM check, etc.), it transmits address information to the first slave station 21.

This will be explained using Figure 2.

First, in order to enable the line driver 51 to transmit, the CPU 31 sets the PAL input terminals 121 to 123 to high level (hereinafter referred to as H) and low level (hereinafter referred to as below), respectively (states 1 and 2 in FIG. 4). (See step 201 in the diagram)
.

Next, the address information of the slave station 21 is transferred to the TXD terminal 81.
(Step 202).

When the transmission is completed, the CPtJ31 sends the line receiver 61
The PAL input terminals 121 and 123 are respectively set to H and L (state 2 in FIG. 4) to enable reception of the signals (step 202 in FIG. 2).

Now that it is ready to receive, start receiving response data from the slave station 21 (step 204), and when all response data has been received (step 205), check whether the received response data is normal or abnormal. Check. If there is an abnormality, that fact is displayed by some means and the process is stopped (steps 206 and 22).
Similarly, if the response data is not returned within a certain predetermined time, the same processing as described above is performed (steps 223 and 220).

These abnormalities occur when the slave station is not operating normally or when the communication cable between the master station and the slave station is disconnected.

If the response data is normally received, the second slave station 22. Similar processing is sequentially performed for the third slave station.

Next, processing on the slave station side will be explained using the first slave station as an example.

After the slave station successfully completes various self-checks (for example, ROM check, RAM check, etc.) after being reset, it enters a data reception waiting state (Step 3 in Figure 3).
01).

When the data has been received, it is determined whether the data is address information or not, and if it is not address information, the device waits for data reception again. (Step 302) When address information is received, the received address is stored in the memory 71.

Next, the transmission enable terminal 104 is enabled to enable the line driver 54 to transmit (step 304), and the response data is transmitted from the TXD terminal 82.

In subsequent communications, the address at the beginning of the data sent from the master station I and the address stored in the memory 71 are checked, and processing is performed only if they are the same.

The same applies to the second and third slave stations. However, the first
If you want to send the same information to all the third slave stations at the same time, set the PAL4 on the master side to state 7 and set the line driver 51 to
53 are all allowed to be transmitted, and the address at the beginning of the data is transmitted as a global address.

FIG. 5 shows an example of data when transmitting address information, FIG. 6 shows data during normal data transmission, and FIG. 7 shows a data format when all slave stations simultaneously send the same information.

In order to simplify the explanation, the CPUs 31 to 34 are 1-chip CPUs, the number of slave stations is three, and the transmission path between the master station and the slave stations is one bidirectional pair. 68000, etc.), the same thing can be done by adding a device for serial communication, and even if there are three or more slave stations, PAL4
and line drivers 51-53, line receivers 61-6
The same thing can be done by simply adding 3, and the same thing can be done even if the transmission line is unidirectional (separate transmission line and reception line).

In addition, the memories 71 to 73 on the slave station side are set to E”P-RO.
If a RAM with M or Hunchley backup is used, the address setting operation is performed only when starting up the system or when it is desired to change the address of a slave station, and the operation is not necessary after a normal reset.

Therefore, there is a jumper on the slave station side to set the address.
There is no need for short switches, rotary switches, etc., so there are no setting errors or erroneous operations, and the slave station address settings and changes are easy to change because they are done by transmission from the master station.

〔Effect of the invention〕

As explained above, the present invention provides a serial communication network consisting of one master station and a plurality of slave stations.
Connect the master station and each slave station with individual lines,
The line driver and line receiver on the master station side can be individually enabled/disabled for each slave station, making it easy to set and change addresses from the master station, and eliminating the need for switches, etc. for address setting on the slave station side. This has the effect of preventing system failures due to incorrect settings or incorrect operations.

[Brief explanation of drawings]

FIG. 1 is an embodiment of the present invention, FIG. 2 is a flowchart explaining the operation on the master station side of the present invention, FIG. 3 is a flowchart explaining the operation on the slave station side of the present invention, and FIG. 4 is a flowchart explaining the operation on the slave station side of the present invention. FIG. 5 is a diagram showing the format for transmitting address information according to the present invention. FIG. 6 is a diagram showing the data transmission format according to the present invention. FIG. 7 is a diagram showing the format for transmitting address information according to the present invention. FIG. H: High bell L: Low level Fig. 4 (Explanatory diagram of the operation of PAL4 of the present invention) Fig. 3

Claims (1)

[Claims] In a serial communication network that has one master station and a plurality of slave stations and each slave station and master station are connected through individual lines, a line driver/line receiver on the master station side means for enabling/disabling the line driver for each slave station, means for enabling the line driver for all stations at the same time, and means for storing the address information of the slave station on the slave station side. A serial communication system characterized in that a driver is enabled for each slave station, unique address information is transmitted to the slave station, and the slave station stores the received address information using the storage means.