PLC-3: unsolicited messages

An unsolicited message is generated in a PLC-3 by programming a Message Instruction. Refer to the PLC-3 Instruction Set Reference for help on how this instruction is programmed. The Message instruction requires several fields to be programmed properly for it to function properly. Following is a sample message rung:

This sample is set to send a message from a PLC-3 with a 1775-SR5 via a DH+ to a KT configured as station 72.

The message control file is B1:0 indicated by CTL=#B001:0000.

The extended address for the 1775-SR5 module is E2.3.1 where E2.3 indicates the module with its thumbwheel set to 1.

The command to be run is: #H072$B4:0=$B4:0, where #H072 specifies the remote station number on the DH+ as 72, and $B4:0=$B4:0 sends the data in B4:0 to B4:0 at the remote station.