Function Overview
The XXMIT function block enables the use of the PLCs serial port for communication under the control of the application program.
The following communication types are supported:
Modbus as Master
Simple ASCII Input/Output
ASCII Input with one or two termination characters
Modem Communication
Function Description
The XXMIT function block sends Modbus messages from a master PLC to multiple slave PLCs or sends ASCII character strings from the PLCs Modbus slave port number 1 to ASCII printers and terminals. XXMIT sends these messages over telephone dialup modems, radio modems,
In case of ASCII messages, there is no control similar to a CRC or a checksum that provides validity checking of the received data.
| CAUTION | |
|---|---|
INVALID DATA Verify the validity of the received data in case of ASCII
messages. Failure to follow these instructions can result in injury or equipment damage. | |
NOTE: To prevent reception of invalid
data due to electrical perturbations, it is advised to use Modbus
messages that include a Cyclical Redundancy Checking (CRC).