Mitsubishi FX3U-232-BD User Manual page 521

FX Series PLC User's Manual - Data Communication Edition
Non-Protocol Communication (RS/RS2 Instruction)
12.4.3 Sending request [M8402 and M8422]
When these devices are set to ON by SET instruction, the PLC starts to send.
1. Detailed contents
When these devices are set to ON by SET instruction, the PLC starts to send. When sending is completed,
these devices are automatically set to OFF.
When communication port ch1 is used, M8402 is set.
When communication port ch2 is used, M8422 is set.
2. Cautions on use
When setting these devices to ON, set the drive condition in the pulse type.
12.4.4 Receiving complete flag [M8403 and M8423]
These devices turn ON when receiving is completed.
1. Detailed contents
These devices turn ON when receiving is completed.
When communication port ch1 is used, M8403 is set.
When communication port ch2 is used, M8423 is set.
Receiving is completed in one of the following three conditions.
• When the PLC receives the amount of receive data specified by the RS2 instruction
• When the terminators are set, and the PLC receives the code set by the terminator
• When data receiving is suspended and the PLC does not receive the next set of data within the time set by
the time-out time setting device
When the receiving complete flag turns ON, transfer the received data to another storage destination, and
then set this flag to OFF.
When this flag is set to OFF, the PLC waits to receive.
2. Cautions on use
When the RS2 instruction is driven while the amount of received data is set to "0", the PLC does not wait to
receive. To make the PLC wait to receive it is necessary to set the amount of received data "n" to "1" or more
and set the receiving complete flag to OFF from ON.
12.4.5 Carrier detection flag [M8404 and M8424]
These devices turn ON/OFF in synchronization with the CD (DCD) signal.
1. Detailed contents
The CD (DCD) signal (channel receiving carrier detection) turns ON when the modem line is established.
When communication port ch1 is used, M8404 turns ON/OFF.
When communication port ch2 is used, M8424 turns ON/OFF.
While the carrier detection flag is OFF, the dial number can be sent.
While the carrier detection flag is ON, data can be sent and received.
12.4.6 Data set ready (DSR) flag [M8405 and M8425]
These devices turn ON/OFF in synchronization with the DR (DSR) signal.
1. Detailed contents
The state of DR (DSR) signal can be checked when executing RS2 instruction.
When communicating port ch1 is used, M8405
When communication port ch2 is used, M8425
The images of M8405 and M8425 are updated during END processing.
*1. Supported in FX
*1
turns ON/OFF.
*1
turns ON/OFF.
and FX PLCs Ver.2.30 and later.
3U 3UC
12 Related Data
12.4 Details of Related Devices (RS2 Instruction)
A
B
C
D
E
F
G
H
I
Apx.
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