Ethernet vs. Remote I/O communications

[ICman]

I am designing a control system around A-B SLC500's. There will be one processor on each of two compressors, and one central station processor. The compressor SLCs will communicate with the station PLC as a supervisory control system.

I started to use Ethernet, but the sales engineer suggested Remote I/O, since the distance was 1000' from compressor to central PLCs.

Should I use Ethernet anyway? Wireless Ethernet? Controlnet? Remote I/O?

Any other suggestions? Thanks,

. . . Steve

 

[xnuke]

The distance requirements for Ethernet cabling are exceeded by what you propose. 300' is about the maximum length for CAT-5 cable. You either need to send it serially (RIO) or send the Ethernet data over fiber. You can easily come up with a cost analysis for this.

xnuke

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[ADMIRALKEN]

Another solution would be to use SLC5/04's and communicate via DH+, I believe maxium distance is well beyond 1000'.
Not as fast as ethernet, but I assume the amount of data passing between stations will be small.


Ken

 

[JesperMP]

How much data, and how fast must the scan update ?

If the requirements are not very high, then even DH485 could do the trick. That could limit the PLC requirements for the two compressors to SLC5/03's or even less than that.

 

[ICman]

I am leaning toward the idea from ADMIRALKEN on using SLC5/04s and DH+.

The most important signals are the remote start/stop commands. Those could be hard-wired between the Station and Compressor PLCs. The other signals (about 200/compressor) are for monitoring purposes from the remote site. They do not need to be gathered often or quickly, since they will be stored in the local (Compressor) PLC/HMI.

We need to know if there is a problem, and what the possible cause is, before sending someone out to the compressor station.

This is good info! Keep the ideas coming!

. . . Steve