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| <== Date ==> | <== Thread ==> |
|---|
| Subject: | Allen-Bradley PLC question |
| From: | Mark Rivers via Tech-talk <tech-talk at aps.anl.gov> |
| To: | "tech-talk at aps.anl.gov" <tech-talk at aps.anl.gov> |
| Date: | Tue, 31 Jan 2023 17:30:30 +0000 |
|
Folks, I have two old Allen-Bradley SLC 500 PLCs with the SLC 5/03 processors. These are communicating with EPICS via the VME 6008-SV1 scanner card, which is connected to a 1747-DCM “Direct Communication Module” in the PLC. These communicate
via the Remote I/O (RIO) protocol. We are planning to eliminate the VME crates on our beamline, but really hope to avoid spending the $50K or so that it would cost to replace the PLCs. I am therefore looking for another way to communicate from EPICS to the PLCs. I am not aware of any device that replaces the VME 6008-SV1, for example a PCI-E card or an Ethernet adapter device. Does anyone else know of one? The SLC-5/03 has an RS-232 serial port 0 that normally uses the DF1 protocol. It is how we program it from a PC, for example. It also has an RS-485 port 1 that uses the DH-485 protocol. It does not have an Ethernet connection. The RS-232 port can be configured to use be a Modbus master. Unfortunately it cannot be configured to be a Modbus slave, which would allow simple connection to EPICS via the Modbus module. However, I could enhance the Modbus module to
add support for acting as a Modbus slave, and the PLC could then connect to the EPICS IOC and send and receive data. Does anyone know of another option, for example with the DH-485 port? Thanks, Mark |