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Allen-Bradley system in Liberty Coach
Our Liberty Coach has the Allen-Bradley PLC system. When I winterized the coach and shut everything down in early December, I can’t remember if the key was set to RUN or REM when I shut it down the coach down and I can’t remember if I turned the key.
Anyone know what the difference between RUN and REM is? I presume PROG is for programming the system, which I don’t know how to do.
Its my understanding there is a battery in the A-B system for when the system doesn’t have power. I’ve shut off the power in the coach again, so I presume the A-B is providing “backup power”. The A-B battery is only a couple/three years old. Does the red light next to BATT indicate a problem? I’m concerned it does.
So far in almost eight years of ownership, the Allen-Bradley system has been flawless.
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17 Replies
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REM is where you want to be. Flip the key to Run, then back to REM
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Mike: Leave on REM even during long period of coach being powered down?
Is the red light by BATT good, bad, or indifferent? Thanks!
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Yes, leave it on REM at all times, You do need a new Battery, change it ASAP. I am not sure how your system is configured, but if you have remote modules writing to the PLC register they won’t be able to write while in Run Mode. It is protection for Programming/Operations. REM is the safest position.
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Thanks for the quick replies! Where do I get a battery? and what kind?
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Good Question, The SLC 500 PLC platform is at end of Life, getting harder to find parts. Allen Bradley is part of Rockwell International, Maybe contact Liberty, or ask them for an Allen Bradley Distributor that might have some old stock. Do not pull the battery out until you have a new one in hand.
Jeff and Lindsay
91 Marathon XL -
Take the old battery and leads to Batteries Plus
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Greg, that is not advisable. Depending on the state of the Eprom, he could lose his program completely.
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Where do I find the little battery for the A-B system? How many of you (Liberty) Prevost owners with an A-B system have changed your own A-B backup battery?
2000 Featherlite H3-45
2024 Jeep Grand Cherokee
Leesburg, FL -
Call Jeff Rowe. I know that he knows where to get them or actually has some.
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Part 1: I had to keep power to the A-B system and not rely on the little battery. So I learned how to run the coach on a single 15amp, 120volt “shore power” cord. We cleaned the refrigerator/freezer out, plugged the coach into the nearest 120volt outside outlet at the house. I turned off every breaker on the electrical panel. I figured out how to reduce the two inverter/chargers’ draw to 5amps each. After a day or so the inverter/chargers went into float, batteries fully charged. So I was covered while parked at the house.
Part 2: I reached out to Bill Doherty at Liberty in North Chicago with my predicament. He found an Allen-Bradley dealer in Green Bay with a tech staff, Werner Electric, that could safely replace the battery. The tech at Werner understood my problem and was really intrigued that an A-B system would be in “an RV”. He found me a source for the battery online (less then $35 IIRC) and said once I got the battery to come to Green Bay and he’d swap it out. The battery arrived while we were in Indianapolis.
Part 3: Went to Green Bay on Tuesday. The tech and his boss came out to see the coach. They were really surprised to see how the A-B system was used by Liberty. The tech brought out his laptop and an RJ-45 (Ethernet) cable to plug in. The tech plugged into our A-B system and it immediately went dead. He unplugged and it wouldn’t wake up. He got another tech from the office to come out. They thought that a fuse was blown or breaker tripped, but confirmed there was power to the A-B system. Another phone call.
What they concluded was that when the Ethernet cable from the laptop was plugged into the A-B system the A-B system sensed the laptop wanted power and the A-B system couldn’t provide that amount of power and shut the system down. They said the program was being preserved on the A-B computer by a capacitor and maybe a watch battery. They popped the A-B computer out of the rack (the computer is really small!), removed the old backup battery, plugged the new one in, plugged the computer back into the rack, and the A-B system immediately lit up. The red BATT light was NOT lit any longer.
I went into the coach the features on the A-B screens worked. SUCCESS!
Going forward, a week before I’m going to power down the coach I’m going to check the BATT light on the A-B computer. If red, I know I need a new battery installed before I shut down the coach.
Here is where I got the battery:
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Dick, Glad you are up and running, but there is no reason for him to connect his laptop, I would have stopped him right there. Have of having the battery in hand, power the system down, pull the Card, remove the old battery, plug in the new Battery, Place the card back, power everything up. That is all it takes. I hope you got him to give you a copy of your program while he was connected?
2025 Marathon H3 / 4th Prevost
21 Ram 1500 EcoDiesel 4x4 -
Dick, my AB system does not like cold temps, it will shut down below 32 degrees or so. The bay heater is a must during cold weather operation. Wondering, is yours sensitive to cold temps too?
Jim
1984 96" with 8V92TA
(remodeled Liberty Coach)
Greenwood, MO -
Mike: Somewhere I learned or was told that the program should be backed up. The A-B system shut down before he could backup the program. He changed the battery without downloading the program. I do have the password.
Jim: I have bay heat in the electric/A-B bay. We have used the coach down to -10*F without interruption of A-B functionality. One of the “to do” items on my coach project list is to get good temp/humidity reporting for the critical bays.
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All you Guys with the SLC 500 should get a copy of your PLC program as soon as Possible, as it is obsolete, Just sayin.
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Hello Mike – is a password required to copy the program?
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