Implementing Modbus TCP/IP (Master and Slave controllers)

A

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Anonymous

I have 3 Twido PLCs with Ethernet connectivity, i.e. with TCP/IP ports. One PLC needs to poll the other two PLCs I/O status and needs to relay or output these status to a mimic board.

In effect, data from two PLCs are transmitted by Ethernet to the main PLC, and the thrid PLC's output card gives the hardwired signals to a mimic board.
 
The master PLC must be a TWDLCAE40DRF. The other 2 PLC's can be any Twido PLC but with Ethernet connectivity, either built in or using the Twidoport module.

You will need to set up messaging (read) from the master to pull the data in from the slave devices.

The TWDLCAE40DRF is the only device that can message as a master over Ethernet. Thi terminology isn't strictly correct as Ethernet uses Client/Server but read the help files and this should confirm.
 
B
Don't know where you are in the world, but I would consider instead of a mimic board, use a small IP65 touch screen in an enclosure. Automation Direct do a price competitive screen and there are many others. They come complete with ethernet connectivity and the neccessary drivers. The use of the touch screen as a display gives, you greater flexibility for additional information later on and you don't need any outputs and very little programming, if any. Just map the I/O data to the screen.

Regards
Bythatmuch
 
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