Hope I can

[colts fan]

Can you have 120 vac from an alternate source to a input card on a 5/04 ? Have to monitor outputs on a PLC 5 to a 5/04 and you can only use 4 peer to peer msg instructions if I understand it correctly.

 

[bkottaras]

Can you have 120 vac from an alternate source to a input card on a 5/04 ? Have to monitor outputs on a PLC 5 to a 5/04 and you can only use 4 peer to peer msg instructions if I understand it correctly.

If I were to do this, I would definetely use interface relais for isolation means.

 

[colts fan]

Just curious I'll end up same power as the PLC5 I'm sure. Yea I've isolated before. Thanks

 

[Mickey]

Or, if the SLC and PLC5 are on the same DH+ network you could use Global Status word (SLC side)
or Global Status Flags (PLC5 side) to pass/monitor the info from one the the other.

See pdf's

 

[TConnolly]

Only if the common for the input card also comes from the alternate source. That means the input card would have to be dedicated and cannot be used for any local inputs and made impossible to connect a local input in the future. For example, Machine A has an 8 out card wired to an 8 in card in machine B and the B common returns to A and all terminals are wired so that nothing may be connected in the future.

Otherwise use interposing relays.

Also, according to code the wires must be ORANGE (NFPA 79 13.2.4.1.) because they could still potentially be energized even when the local disconnect is off.

Regarding messaging, can't you have the PLC/5 MSG Write some of the data and also have the SLC5/04 MSG Read the rest if you have limitations?

 

[James Mcquade]

in addition to what TConnolly said,

you MUST also have a placard on the enclosure door stating that the machine panel also has an alternate source of power to alert maintenance to the electrical hazard.

regards,
james