JPH02237247A - System for controlling loop type transmission reception circuit - Google Patents

Abstract

PURPOSE:To easily detect a fault and to prevent the deterioration of a whole loop at the same time by monitoring reception data and transmission data, comparing transmission reception data with transmission reception monitor data, and detaching them from a transmission line when they are abnormal. CONSTITUTION:When the output polarities of line receivers 2 and 3 differ, 'H' is outputted from an exclusive OR circuit 4. When the polarity of the input of a line driver 6 differs from that of the output of a line receiver 7, 'H' is outputted from the output of an exclusive OR circuit 8. The output of an OR circuit 9 is inputted to the D terminal of a flip flop 10. When reception data differs from transmission data, the output of the flip flop 10 turns off a transistor 17 through a resistance 15, interrupt the current of a relay coil 16 and detaches data from the data transmission line. Thus, the fault of a secondary station can easily be detected, and the deterioration of the whole loop can be prevented.

Description

[Detailed description of the invention] “Industry” second field of use] The present invention relates to a loop type transmitting/receiving circuit control system.

[Prior Art] There are two types of connections for data communication devices, such as facing, loop, and loop connections, and the concept of the loop connection method according to the present invention is shown in FIG.

In Fig. 2, 21 is a primary station, 22 to 25 are secondary stations,
26-30 are transmission circuits (line dry/<), 31-
35 indicates a receiving circuit (line receiver). In the data transfer system connected in this way, poll link information for soliciting data to be sent is sent from the peer transmission circuit 26 of the primary station 21 to the secondary stations 22 to 25, and the polling information is used to send data to the secondary stations 22 to 25. Through the receiving circuit 32, the transmitting circuit 27 of the secondary station 22
The signal is then input to the transmitting circuit 33 of the next secondary station 23.

Thereafter, the secondary station transfers the polling information to the lower secondary station in the same manner as described above, and finally returns to the receiving circuit 31 of the primary station 21. If the secondary station needs to transmit data, it transmits the data following the polling information from the primary station 21.

Next, FIG. 3 shows the configuration of a conventional secondary station. In the circuit shown in Fig. 3, 3-1 to 3-6 are relay contacts, 42 is a line receiver, 44 is a transmission/reception control circuit, 43 is a line driver, 45 is a switch, 46 is a relay coil, 48 is a resistor, and 47 is a transistor. It is. In such a configuration, polling information from the primary station is sent to relay contact 3-
1 and 3-2 to the line receiver 42.

The output of the line receiver 42 is input to the transmission/reception control circuit 44, and the polling information is input to the line driver 43.
is output to. If the secondary station has transmission data, the data is output to the line driver 43 following the polling information. Line driver 43 is relay contact 3-3.3-
4 to the next secondary station.

When the power source of this device is disconnected, the information of the primary station is relayed to relay contact 3-1.
~3-4, the data is directly transferred to the next secondary station.

switch 45, relay coil 46, transistor 47,
The circuit consisting of the resistor 48 is used to disconnect from the data transfer path when the power of the secondary station is turned on.By setting the switch 45 to the G side, the drive current of the relay coil 46 is cut off, and when the power is turned off, It will be the same as

[Problem to be Solved by the Invention] In a data transmission line connected in a loop as described above, the problem is that even if a failure occurs in the transmitting/receiving circuits 42 and 43 of one of the secondary stations, the entire loop is a hindrance. Furthermore, if the failure mode is permanent, it is easy to discover, but if it is intermittent, it takes a lot of effort and time to discover the failure mode.

Therefore, an object of the present invention is to provide a loop-based transmitting/receiving circuit control system that can easily detect a failure in a secondary station and prevent the entire loop from going down.

[Means for Solving the Problems] According to the present invention, in a loop data transmission path,
a monitor means for monitoring the transmission/reception line; a detection means for comparing the monitoring result with the transmission/reception data to detect the presence or absence of a difference; a means for retaining the detection result of the detection means; A loop-type transmitting/receiving circuit control system is obtained, which is characterized in that it includes a means for disconnecting from the data transmission path under normal circumstances.

[Example code] Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows a circuit block diagram of an embodiment of the present invention.
-1 to 1-6 are relay contacts, 2, 3.7 are line receivers, 5 is a transmission/reception control circuit, 6 is a line driver, 4 8
is an exclusive OR circuit, 9 is an OR circuit, 10 is a flip-flop, 11,] . 4,1.5.1 9 is resistance, :l
．． 2.17 is a transistor, ]3 is an LED, 16 is a relay coil, ]8 is a switch.

In the circuit configured in this manner, polling information from the primary station is input to line receivers 2 and 3 via relay contacts 1-1, 1-2. The output of the line receiver 2 is input to the transmission/reception control circuit 5 as received data, and at the same time is input to one terminal of the exclusive OR circuit 4. The output of the line receiver 3 is input to the other terminal of the exclusive OR circuit 4. The output of the exclusive OR circuit 4 is outputted as "H" when the output polarities of the line receivers 2 and 3 are different, and is input to the OR circuit 9.

Next, the output of the transmission/reception control circuit 5 is inputted to one terminal of the line 1 driver 6 and the υ1 alistic OR circuit 8. Line driver 6 poll information output is relay contact 1
−3,]. 1 when transferred to the next secondary station through -4.
1, +i is input to the line receiver 7, and its output is input to the other terminal J of the exclusive OR circuit 8. Here, when the polarity of the human power of the line driver 6 and the output of the line receiver 7 are different, the output of the exclusive OR circuit 8 is ゛H.
" is output and input to the OR circuit 9. The output of the OR circuit 9 is input to the D terminal of the flip-flop 10,
The flip-flop 10 is set/reset by the clock signal from the transmission/reception control circuit 5 depending on the input state of the D terminal.

The output Q of flip-flop 10 is
is input to the OR circuit 9 to maintain the set state. If there is a difference between the received data and the transmitted data, the output Q turns on the transistor 12 through the resistor 1, and turns on the LED 13. Resistor 14 is a current limiting resistor. Furthermore, when there is a difference between the received data and the transmitted data, the output Q of the flip-flop 10 turns off the transistor 17 through the resistor 15 and does not cut off the current in the relay coil 16. The switch 18 is a switch for disconnecting from the data transmission path while the power remains on.

[Effects of the Invention] As explained above, the present invention monitors received data and transmitted data, compares the received data with the received monitor, and compares the transmitted data with the transmitted monitor data, and as a result, disconnects from the transmission path. By doing so, it is possible to easily detect failures, and at the same time, it has the effect of preventing the entire loop from going down.

In receiver, 4, 8... exclusive OR circuit, 5...
・Transmission/reception control circuit, 6... line driver, 9...
OR circuit, 16...Flip-flop, 11, 14
, 1.5.19...Resistor, 12.17...Transistor, 13...LED, 16...Relay coil, 18
Switch, 21...Primary station, 22-25...Secondary station, 26-30...Line driver, 3 1-3
5-... Line receiver, 3-1 to 3-6... Relay contact, 42... Line receiver, 4 3-... Line driver, 44... Transmission/reception control circuit, 45... Switch, 46... ...Relay coil, 47...Transistor, 48...Resistor.

[Brief explanation of drawings]

FIG. 1 is a circuit block diagram of an embodiment of the present invention, FIG. 2 is a diagram showing a general loop connection, and FIG. 3 is a circuit block diagram of a conventional example.

Claims (1)

[Claims] 1. In a loop-type data transmission path, a monitor means for monitoring the transmission/reception line, a detection means for comparing the monitoring result with the transmission/reception data and detecting the presence or absence of a difference, and means for holding the detection result of the detection means. and means for disconnecting from the data transmission path in the event of an abnormality based on the detection result.