John Soltesz
Member
I have a project to replace 11 OPTO22 controllers on an RS485 loop controlling makeup air heaters. The OPTO stuff has been at times unreliable since installed in 1996. The units are monitored along with setpoint changes running some OPTO software as the HMI. Each unit runs independently. The hardware isn’t as robust as the rest of our AB or GE PLCs so I am testing ML1400s and will use either a PC based HMI or PV+, or maybe a C-more touch screen. I have the program mostly converted and running on two ML1400s and a C-more all via DH485 in my office.
So my question is can I use the existing RS485 cabling (Belden 9729) running around the perimeter of the building (875’x260’ foundry/rolling mill), about 2600 feet in conduit with the longest length about 330’ between units? If we can use the existing cable we will save a big pile of money. Or will there be issues with the DH485 communications that will remove what little hair I have left? We have other DH485 controls going over that distance underground to a lagoon with only the occasional lightening induced dropouts. Right now with the loop in question we get some scanning overruns while trying to chart but without charting things look good. We do not have a process LAN close to any units to use if we would want to use the Ethernet ports. I would like to stay away from radios; I use them with success in other areas but prefer to be hardwired.
I am going to ask the Black Box folks if their Ethernet extenders (LB532A-L, R, and M) would work on the Belden cable. If they work it would be less costly than a real dedicated LAN or getting radios to work reliably. Is there an issue with the AB ML1400 Ethernet running on this type of hardware?
So gut feelings? This may be my last sizable project before I retire next year and I don’t want a headache legacy.
So my question is can I use the existing RS485 cabling (Belden 9729) running around the perimeter of the building (875’x260’ foundry/rolling mill), about 2600 feet in conduit with the longest length about 330’ between units? If we can use the existing cable we will save a big pile of money. Or will there be issues with the DH485 communications that will remove what little hair I have left? We have other DH485 controls going over that distance underground to a lagoon with only the occasional lightening induced dropouts. Right now with the loop in question we get some scanning overruns while trying to chart but without charting things look good. We do not have a process LAN close to any units to use if we would want to use the Ethernet ports. I would like to stay away from radios; I use them with success in other areas but prefer to be hardwired.
I am going to ask the Black Box folks if their Ethernet extenders (LB532A-L, R, and M) would work on the Belden cable. If they work it would be less costly than a real dedicated LAN or getting radios to work reliably. Is there an issue with the AB ML1400 Ethernet running on this type of hardware?
So gut feelings? This may be my last sizable project before I retire next year and I don’t want a headache legacy.
