Ge fanuc 90 series

[balla]

I have managed to communicate between two series 90 PLC's using SNP Comm_REQ and switch a output on the slave from a INput on the Master but I am unable to switch a Input on the slave to controla Output on the Master.Does anyone have a sample Versa Pro program that can do this or if not details of the logic. Thanks Balla

[Steve Bailey]

Serial communications doesn't sound like the most efficient way to go about it, but if you're determined to do it that way... Presumably, to have the master's %I point control the slave's %Q, you're writing the status of the master's input from the master to some memory location in the slave and there is ladder logic in the slave to turn on the output. Either that or you're writing directly to the slave's %Q memory. To have the slave's %I point control the master's %Q, you will need to have the master read the status of the input from the slave and store the result in some memory location in the master. Then add ladder logic to turn on the master's %Q point. A Genius communications module could accomplish the same thing without having to write any additional ladder logic. It would also give you much more frequent updates. You could also do it with ethernet or Device Net or Profibus.

[Tank_Harvey]

Just to Add In the PLC you should not write to a input table with any comms (except with genius IO like stave said). If you are using snp to write to a input table then the status might be getting their but the next PLC scan it would be overwritten by the real IO. Just a thought