g.mccormick
Lifetime Supporting Member
We are talking to a potential customer that has a test rig that the computer has died on. It is confusing to me what exactly they have, but this is what I think I know.
1. There is an SLC5/03 system with digital and analog ins and outs that controls part of the rig. This SLC system talks to the computer with MODBUS (atleast it is believed to be MODBUS).
2. The SLC system controls a vfd to control air flow. This is believed to be 4-20ma and digital i/o.
3. There is a second Allen Bradley plc (maybe a micrologix). The second PLC controls a coolant system.
4. The SLC system sends setpoints and process variable to the micrologix system via analog outputs.
5. In my reading, it appears that the SLC cannot be a modbus slave, it can only be a modbus master.
6. Our software can only be a modbus master, cannot be a modbus slave.
7. One option is that we replace the SLC system with IO that we control from our software. This would probably be the most straight forward, but don't know if potential client would go for it.
8. Another option that I have thought up is to put a Automation Direct Click PLC in line. Let the SLC be that master to the Click on port 2 (rs232) we could be the master to the click on port 3(rs485). I don't know if that would work or not.
We do not do PLC systems and have no prior knowledge of Allen Bradley PLCs. I personally have started to play with PLC as a personel play/learning experience.
Our system is a full data acquisition and control system running on Linux.
Any thoughts?
Thanks
1. There is an SLC5/03 system with digital and analog ins and outs that controls part of the rig. This SLC system talks to the computer with MODBUS (atleast it is believed to be MODBUS).
2. The SLC system controls a vfd to control air flow. This is believed to be 4-20ma and digital i/o.
3. There is a second Allen Bradley plc (maybe a micrologix). The second PLC controls a coolant system.
4. The SLC system sends setpoints and process variable to the micrologix system via analog outputs.
5. In my reading, it appears that the SLC cannot be a modbus slave, it can only be a modbus master.
6. Our software can only be a modbus master, cannot be a modbus slave.
7. One option is that we replace the SLC system with IO that we control from our software. This would probably be the most straight forward, but don't know if potential client would go for it.
8. Another option that I have thought up is to put a Automation Direct Click PLC in line. Let the SLC be that master to the Click on port 2 (rs232) we could be the master to the click on port 3(rs485). I don't know if that would work or not.
We do not do PLC systems and have no prior knowledge of Allen Bradley PLCs. I personally have started to play with PLC as a personel play/learning experience.
Our system is a full data acquisition and control system running on Linux.
Any thoughts?
Thanks
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