Omron CQM1H-SCB41 Operation Manual page 53

Application Procedure
38
6. Program the host and the CPU Unit and execute the programs.
Host-initiated Communications: Host Link Commands
A program must be prepared in the host to send Host Link commands to
the PC and receive responses.
Host
Command
PC-initiated Communications: TXD( ) Instruction
TXD( ) must be included in the ladder program to send data from the PC
to the host.
Host
Data
Program to send
commands and
receive responses
Serial Communications Board
Response
Program to send
responses
Serial Communications Board
CPU Unit
Section 4-2
TXD( )