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Drudawgshu September 19th, 2005 04:22 PM

PLC network
 
Im designing a conveyor system that contains 27 lines. Each line has 10 120Vac inputs and 20 120vac outputs. I would each line to have its own panel of I/O and connect all lines to a SLC 04 over a network configuration. Should I use the flex I/O? over a devicenet network? controlnet network? I must use the SLC 04 processor, Any ideas of the best way to communicate to this I/O??

any suggestions would be appreciated.
thanks,
Drew

MartB September 20th, 2005 10:55 AM

The choice of remote I/O is usually a physical one. Is it pratical to run long mulitple wire lengths to reach conveyor motors, sensors, etc (I'm making assumptions here).
Communication choices are often based on speed. Is it neccessary to have high speed communications ?
As for 120Vac inputs and outputs, would it be more pratical/safe to have relays operating these? and simply supply I/O to banks of relays in remote panels via devicenet (Just thinking out loud really)?

Maybe more detail would make your predicament easier to understand.

OkiePC September 20th, 2005 11:35 AM

You have to choose a network type and and I/O type.

Your main choices for a network type with a 5/04 are going to be RIO, C-NET, or Devicenet. I have zero experience with devicenet, but lots with RIO. It is very reliable, fairly easy to configure, and fast enough for most applications. Controlnet is much more difficult to work with, but very fast. For controlnet, you will need RSNetworx for Controlnet software, tools to make good BNC connections, and a lot of little parts and pieces to put it all together. RIO is extremely easy to work with. One 3 wire cable daisy chained from the scanner to all the adapters with terminating resistors at the end links, a little configuration and you're done.

With DNET you can use point i/o, flex i/o, or compact i/o. With RIO you can use block i/o, flex i/o, or slc i/o. I have never used compact i/o. I don't particularly like flex I/O. I do like SLC i/o, and have used block I/O with no problems.

Block I/O has a built in comm adapter and is available with both inputs and outputs, but for 120vac outputs, the most you can get in a combo unit is 16 outputs. (You can get 32 outputs in a single unit, and 32 inputs in another single unit) If you used 24VDC for control, you could use a single unit for each station with 32 inputs and 32 outputs. Block I/O has removable terminal blocks for easy replacement, but with 120vac control power, you'd have two of them per panel. I thinks it's more rugged than flex i/o, but takes A little more space:
(1)1791-32B0 (or 16A0)
(1)1791-OA32

Putting a four slot SLC i/o panel in each station will cost more but take less space than two block i/o modules:
(1)1746-A4 (Chassis)
(1)1746-P2 (Power Supply)
(1)1747-ASB
(2)1746-OA16
(1)1746-IA16

I would weigh (heavily) into the decision what types of communications and i/o are already in use in the plant.


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