iFIX IGS: Channels & Devices Setup?

All,
I have a question regarding the typical setup of Channels and Devices in IGS (using iFix).

Every system I've seen uses one device (PLC) per channel. I haven't seen any setup where there are multiple devices on a single channel.

Are there any advantages to having, or not having, multiple PLCs or devices under a single channel in IGS? Under what instances would you do this?

Thanks

Yes, each channel is its own communications thread. You can have a minimum of 100 channesl per device protocol selected in the IGS server. For ControlLogix you can have 256 channels.

So if you have 20 devices and they were each on their own channels then you could talk to them simultaniously. If you put all the devices under one channel they the are communicated to synchronously, one device at a time. This mesns that a poll cycle does not complete untile you have polled all the devices once. If a device has communications problems then that adds time to the completion of the poll. When each device is on its own channel then a device failur has no impact on the other devices.

Thanks, I figured it was something like that but wasn't sure.

Are there any instances (that you can think of) where you would want multiple devices on a channel (there poll time isn't a concern, I'm guessing)?

Usually when you connection methodology restrics connectivity. An Example would be a radio or satelite modem that only allows one connection through it. In that case you would place all the devices on once channel so that we are establishing a single socket connection through it.

Thanks Fred.

Enjoy the foliage, I figure we have a week or two so before things start to fade.

Several CHannels and 2 devices

Hi

iFIX 5.5
IGS driver

I have a similar problem.

I have 20 channels(A13, A17,..A53) and 2 devices(PLC1 and PLC 2). Each channels has one of the devices or both.

E.g.
If I make a reference to PLC1 through channel A23, it connects fine. If I make the reference through channel A24 to the same PLC1 there is no connection.

Is it a problem, that all the PLC1s are configured the same. Same port, same IP ect.

I hope someone can help.

Best Allan G