mm-pm15-403

Sorry I'm not a programer. But can a second or slave be added? If so what is maximum distance
thanks

For those who don't recognize the part number, the MM-PM15-403 is a PanelMate 1500 HMI brand labeled as Modicon.

I'll need more information about what its connected to in order to give you a more definitive answer. The answer to your question is "maybe". Generally, HMI units, particularly those of that vintage, are communications "masters" and the PLCs they communicate with are "slaves". That means the HMI is the entity that initiates all data exchanges between the themselves and the PLC. The PLC only "speaks when spoken to". It's a lot easier to have one HMI communicate with two or more PLCs than to have two or more HMIs talking to one PLC.

If your PLC has a second serial port, you may be able to use that to communicate with an additional HMI.

The "it depends" part is because that particular model had a Modbus Plus daughter board as an option. If the existing unit is using Modbus Plus, then it is possible to add another HMI to the same network. I don't know the distance limitations off the top of my head.
The PanelMate 1500 could also have an Allen Bradley Data Highway daughter board which would also permit additional HMI units on the same network.
Regardless, that HMI is an old unit, no longer in production.

Its used with an STX PREMIUM DSY08R5A
I has 3 ports on the pm
hope this helps
Thanks much

DSY08R5A looks like an 8-circuit relay output card rated for 5 amps per contact. Not the sort of module that HMI panels are generally communicating with.

Three ports on a PanelMate 1500. That sounds like it has a daughter board. The base unit only has two ports, one for programming or PLC communications, the other strictly for PLC communications.