Table of Contents
Advertisement
5.2 MEWTOCOL-COM Master Communication (RECV)
5.2.1 Read Data from an External Device
Instructions
In master communication, PLC has the sending right, and executes communication by
sending commands to devices that support MEWTOCOL, and receiving responses.
Messages in accordance with the protocol are automatically generated by PLC. In the user
program, reading and writing can be done simply by specifying the station no. and memory
address and executing SEND/RECV instructions.
PLC
DT100
100
DT101
0
・・・・・・
・・・・・・・・
・・・・・・
・・・・・・・・
Sample program
Send commands from the COM1 port of the CPU unit, read data from the data area of an
external device (station no. 1) DT400 - DT401, and write the content into PLC's data register
DT100 - DT101.
Confirm that the unit is in the master mode (XC), and that the sending process is not in
progress for the same port (YC), and start up the SEND instruction.
In the UNITSEL instruction, specify the slot No. (U0) and the COM. port No. (U1).
In the RECV instruction, specify and execute the partner station no. (U1), initial address
(DT400), No. of data (U2), and initial address on the PLC side to save data (DT100).
R0
DF
（
）
Master
communication
R100
Clear to send flag
RECV.US
5.2 MEWTOCOL-COM Master Communication (RECV)
Command message
%01#RD0040000401 (BCC) C
%01$RD64000000 (BCC) C
Response message
Specify and read station no. and address based on RECV instruction
XC
YC
Master
communication
Sending active flag
UNITSEL
U1
DT400
S1
S2
R
R
R100
Execute
RECV
U0
U1
S1
S2
U2
DT100
DT0
n
D1
D2
External device supporting
MEWTOCOL-COM
DT00400 100
DT00401 0
・・・・・・
・・・・・・・・
・・・・・・
・・・・・・・・
Starting conditions for RECV
execution
Clear to send flag: ON
Sending active flag: OFF
Settings for communication port
S1: Slot 0
S2: COM1
RECV processing
S1: Partner station no. (U1)
S2: Data address (DT400)
n: No. of data (U2)
D1: Data saving area (DT100)
D2: Execution result code (DT0)
5-3
Advertisement
Table of Contents
