Remote Serial Cards?

[brucek]

It appears that serial cards cannot be used in remote racks. We have moved toward putting all our drives as close to the motors as we can to try to limit the amount of noise generated. Anyway, i'm thinking of using modbus to control the drives and also read info from the drive. These are Benshaw rsi S4 drives and only have rs 485 serial comms. We have remote racks at places around our plant and would be nice to have remote serial cards at certain places to address some of these drives. My question would be is there a plan for serial cards that can be placed in remote racks? Is there a reason why it wouldn't work? Or is this ,SGW-MB1511-T ethernet to serial device the way to accomplish this task?

[BobO]

It's just hard due to the way serial ports are handled. Serial needs to be serviced relatively fast at higher baud rates, and may or may not get offended by buffering delays in both directions. Ethernet is easily fast enough to carry the traffic, but scan dependent latency can completely wreck protocols. Rather than put out solutions that are spotty and work or fail intermittently, we choose not to go there.

I'm generally a fan of sticking a small controller like a BRX out on the drive(s) and talk to it via Ethernet. While localizing the drive comms, that also allows you to put some additional logic at the drive, which can be useful in the event of a network failure.

Currently you can have 2 RS485 ports (which can talk to multiple drives each), but we are also developing a SERIO for BRX.

[DLTimmons]

I bumped in to this issue a few years back on a 205 base system. I wound up using a do more in reach remote rack and just Modbus the data I need at each rack. At the time the remote base controller was only 50 bucks less than a Do-more. So I used distributed control.

[brucek]

Thanks for the reply so quickly. I never though of using the brx as a remote but seems like the best plan thank you all.

[ATU]

The M series CPU's are perfect for that application, if you don't require any I/O at the moment, but have the flexibility to add it in the future.