I'm working on an application in which the customer will have a ControlLogix PLC, and we plant to use ControlNet to interface with some Variable Frequency Drives and in so doing, reduce the number of PLC I/O points that would otherwise be hard-wired to conventional PLC I/O modules (in this case,
1756-IA16Is and -OA16Is, if memory serves me right.) I am specifying an A-B
1203-CN1 communications module to be put in the VSD's compartment. (BTW, the
1203-CN1 has 2 coaxial cable ports and an Ethernet port; coaxial cable is the default way to communicate using ControlNet. The 1203-CN1 also has a
9-pin, I think, male connector for a mating cable which runs to the drive.)
I have some questions:
- This drive has a Bypass mode in which it can run as a full-speed motor. I'm trying to figure what it would take to allow the 1203-CN1 module to pick up this input. We'll have a 3-position AFD-Off-Bypass switch on the drive's compartment; maybe the ControlNet link could somehow be used to monitor the Bypass position. Does anyone know how something like this work, or how the "Drive in Bypass" signal could be communicated to the 1203-CN1 module?
- We will bring 1 to 3 other inputs into the drive's compartment from the field that are unrelated to the drive's internal workings (e.g., a high temp. alarm from a non Allen-Bradley device.) There be a relay for each with dry contacts in the drive compartment. Does anyone know if a dry contact representing any status signal can be picked up and communicated to ControlNet somehow?
I'd love it if anyone could give answers they're darned confident about.
Mike