Slc 5/04 dh+

I have 2 SLC 5/04 plc's using Data highway plus, daisy chained. They are controling 2 different processes. I think they were connected together only for the convenience of being able to communicate with laptop to either one from the other.
They each have their own HMI touchscreen. They are both working fine, I would just like to know if I can use inputs from 1 plc to turn outputs on in the other plc. And how would the addressing be. Any information would be appreciated.

You can use the MSG instruction to communicate between them. You can read and write data from either or both PLCs. The messaging is subject to communication delays, and is not intended for controlling I/O, but for situations that do not require high speed and can tolerate the possibility of communication losses it might be okay.

In RSLogix500, go to Help > SLC Instruction Help > MSG. There are links to help files specific to the 5/03 and 5/04.

Paul

That is just what I am looking for. THANKS.

If you only need to transfer one word, you can use the global status word instead of using a MSG instruction. Each node on the network has a global status word. You use standard instructions to MOVe data to S:99 on the source PLC, on the read PLC, S:100-S1:163 (octal), contains the status word from the other nodes. S:100 is for node 00, S:107 is for node 7, etc...

You can see the values of all the status words by opening the status file and going all the way to the far right, the last tab is the global data tab. If you want to use the global status word, while on the tab, enable both bits

From the help files:

This is the word reserved to hold the SLC 5/04 (OS401) controller's global status data that is to be transmitted with each DH+ token pass packet over channel 1.

Transmit Control Bit S:34/3
When this bit is set (1), the controller transmits the global status word with every token pass. When this bit is clear (0), the controller passes the token without the global status word. The default state of this bit is 0.

Receive Control Bit S:34/4
When this bit is set (1), the controller places the global status word that it receives from other nodes on the DH+ network into the Global Status word (S:100 through S:163). When this bit is cleared (0), the controller ignores the global status word that it receives from other nodes on the DH+ network. The default state of this bit is 0.

S:100 to S:163 Node
These words comprise the System Status file. This file size is consistent with the number of nodes on the DH+ network and contains the global status words received by these nodes. When received, each DH+ node's global status word is placed in this file and indexed to its node number.

You can use the Global Status File to send a high-speed broadcast to all processors on a network in one token rotation. Using an MSG instruction would require as many MSG instructions and token rotations as there are processors on the network. This is useful for such activities as sending start/stop signals, synchronizing processors, and synchronizing clocks.

I agree with Ken. The global status words are automatic and require no code!