Table of Contents
Advertisement
■For receive data
Header
DLE
STX
Low
High
order of
order of
SD8623
SD8623
Receive data
Operation of control line (RS-232C)
RS-232C communication is full-duplex, bi-directional communication. When using half-duplex, bi-directional communication,
pay attention not to turn ON the sending request flag while receiving. If set to ON, the PLC starts to send and as a result, the
counterpart equipment may not be able to receive data, and the sent and received data may be destroyed.
In full-duplex, bi-directional communication, the sending wait flag does not turn ON.
However, in the case that control is standard mode or interlink mode, the sending wait flag remains ON while DR (DSR) is
OFF and the PLC is waiting to send.
Control line not used
RS2 instruction
OFF ON
execution
SD(TXD)
Send data
Sending request
OFF
RD(RXD)
Receive data
Receiving
complete flag
Start of waiting status
for receiving
Data area
Terminator
35H
36H
37H
38H
DLE
Low
High
Low
High
Low
order of
order of
order of
order of
order of
D200
D200
D201
D201
D202
Sum check code target
Low-order bits of D200
35H
High-order bits of D200
36H
Low-order bits of D201
37H
High-order bits of D201
38H
Low-order bits of D202
10H
High-order bits of D202
03H
EDH
Message
Message
1
3
ON
ON
Message
2
OFF
ON
Reset the flag from the program.
This flag must be turned off to receive the next data.
The order is different
Sum data
from the data area.
ETX
45H
44H
High
High order
Low order
CR
LF
order of
of sum
of sum
D202
SD8563
SD8563
Comparison
4544H
Converted into ASCII codes
Message
5
ON
Message 4
6 NON-PROTOCOL COMMUNICATION
ON
6.7 Programming
6
173
Advertisement
Table of Contents
Troubleshooting
