Switching CLX "ownership" of Remote I/O on the fly?

[paulengr 44]

Can it be done? Here's my situation... We have 8 "pump sleds" in a mine. All are interchangeable with each other. We also have 3 "pit cars" which control the system. Any 2 pit cars can be active at a time and can control up to 3 pumps each in series with each other (one primary plus up to 3 boosters). Everything is tied together with wireless links. Right now this is all done with old GE 90-30 (did I get the numbers right?) and Genius I/O. The way that the configuration is done is that there are selector switches (the old rotary BCD stuff) which select pit cars. There is a PLC on each of the pumping sleds but in reality it's all but treated as remote I/O. We're talking about modernizing this mess and going with Allen Bradley PLC's since that's the plant standard. But I've got a bit of a dilema. I could easily do it by putting a PLC on every component. If I did that, the most cost effective route seems to be Micrologix 1400. However if possible I'd like to go with a CLX-based processor. If I go with CompactLogix due to the fact that the L23E's on-board I/O is DC only (and there's a lot of starters and other AC loads to contend with) and it only supports 2 more 1769 modules, that pushes me into using an L32E. This blows the costs right out of the water to the point where there's a lot of questions about doing the conversion at all. Since effectively we're just treating the pumping stations as remote I/O anyways (and what little logic there is for manual control and such could easily be done with DNY41R's or similar DeviceLogix modules), I was thinking about treating the pumping stations as remote I/O. Therein lies the dilema...I can't control whether or not one of the 3 "pit car" PLC's is always online, so I need to be able to effectively configure "ownership" over the pumping sleds on the fly with SSV/GSV instructions for instance if I treat them as remote I/O. Is there any effective way to do this? My alternative would be to put Micrologix 1400's on everything, but I was hoping to stick with CompactLogix since the electricians are going to see ControlLogix processors everywhere else they go in the plants, and part of the reason for upgrading is to get away from all this orphan stuff.

[Ken Roach 194]

You can use SSV instructions to the Mode attribute off the Module Object (INT datatype, bit 2 = inhibit) to switch on and off the I/O connections over EtherNet/IP from a controller. You would define all 8 of the Pump Sled drops (FLEX or POINT I/O, I imagine) and enable only the ones you wanted to use. Since you had selector switches to make it work previously, you could re-use such switches or another selection mechanism to tell the Pit Car controller which Pump Sleds to take over. Is the existing GEnius bus running over this wireless system ? How would you logically deal with a circumstance where two Pit Cars were selected to control the same Pump Sled ? If this were my system, I would put a controller at each pump sled, instead of attempting wireless remote I/O on EtherNet/IP. I've had a lot more experience than I'd like troubleshooting wireless IP systems and I very strongly recommend against running cyclic traffic like I/O connections across any type of wireless system. Edited 15 Apr 2009 by Ken Roach

[BobLfoot 302]

Yes you can switch ControlNet Remote I/O "on the fly" The best example of this I've seen was in the ControlLogix Redundancy System 7.52 User Manual. This was ControlLogix Redundant processors using ControlNet I/O but without and SRM module to synchronize data. The GSV and SSV instructions in that manual would be useful I think. The bad news is I've searched for 30 minutes in the knowledgebase and cannot turn it up.

[paulengr 44]

I agree. On the other hand, they already have a fully functional system with zero hiccups. Hard to argue with success. And the environment is...let's just say distributed control is the best thing going. They already tear up the "little" 4/0 SHD-GC cabling (2.75" OD with jackets being what they are...this is salt-cured 5kV mine duty trailing cable), to say nothing of Ethernet. And the distances preclude anything but fiber which is again, not really very tolerant of the conditions unless we could redo all the power cables with fibers embedded in them...they exist but at about $26/foot with tens of thousands of feet of cable, the cost to redo all the cables makes it a no-go. Current "splicing" technology is fusion, which might just be practical with single mode fibers, but requires lots of training and can't be done outdoors in dusty environments. I considered power-line based modems but I'd need an obscene number of transformer bridges and I'd be going back and forth across 24kV, 7.2kV, and 4160 buses to bridge everything in order for the power line stuff to work (if it can even give me the required range). These pumping systems are 1500 HP motors running 30"x30" slurry pumps on 4160.

[paulengr 44]

I agree. On the other hand, they already have a fully functional system with zero hiccups. Hard to argue with success. And the environment is...let's just say distributed control is the best thing going. They already tear up the "little" 4/0 SHD-GC cabling (2.75" OD with jackets being what they are...this is salt-cured 5kV mine duty trailing cable), to say nothing of Ethernet. And the distances preclude anything but fiber which is again, not really very tolerant of the conditions unless we could redo all the power cables with fibers embedded in them...they exist but at about $26/foot with tens of thousands of feet of cable, the cost to redo all the cables makes it a no-go. Current "splicing" technology is fusion, which might just be practical with single mode fibers, but requires lots of training and can't be done outdoors in dusty environments. I considered power-line based modems but I'd need an obscene number of transformer bridges and I'd be going back and forth across 24kV, 7.2kV, and 4160 buses to bridge everything in order for the power line stuff to work (if it can even give me the required range). These pumping systems are 1500 HP motors running 30"x30" slurry pumps on 4160. Edited 15 Apr 2009 by paulengr