7.3 MEWTOCOL-COM Master Communication (RECV)
7.3.1 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.
External devices that
support MEWTOCOL-COM
%01#RDD0040000401 (BCC) C
R
%01$RD64000000 (BCC) C
R
Command messages
Response messages
DT100 100
DT101 0
・・・・・・ ・・・・・・・・
・・・・・・ ・・・・・・・・
DT00400 100
DT00401 0
・・・・・・ ・・・・・・・・
・・・・・・ ・・・・・・・・
PLC
Perform reading by specifying Unit number and
address using the RECV instruction
■
Sample program
● Send commands from the COM.1 port of the CPU unit, read data from the data area of an
external device (station no. 1) DT400 to DT401, and write the content into PLC's data
register DT100 to 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).
(Note 1) The unit number and COM. port number in the above program is applied when the COM.1 port of the
CPU unit is used.
7.3 MEWTOCOL-COM Master Communication (RECV)
WUME-FP7COM-07 7-5
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