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Allen Bradley ML1500 error

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UKpete

UKpete

Electrical
Joined
Jan 6, 2002
Messages
463
Location
GB
Hi, this is a novice area for me. Have an old fairground ride with this AB ML1500 plc, the fault light has started flashing, displayed fault code is 0080. Looked this up on-line and it stated that the terminator module is disconnected. It definitely isn't and looks fine!
Is it worth trying a new module?
We don't have RSLogix or similar software.
Grateful for any advice
 
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Well if you have a long bus or if it is just a long I/O module it can be a bad connection somewhere.
Then the communication on the bus or the backplane on the I/O modul can't communicate.
But the fault message will probably be that there is no "end resistor" at the end terminating the bus or the I/O module since it is needed to make the communication working in the first place.

Have never worked with Allen Bradley PLC:s but most buses are usually built on the same principle.

Best Regard A


“Logic will get you from A to Z; imagination will get you everywhere.“
Albert Einstein
 
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Disassemble the backplane modules and reassemble. Sometimes a connection will get flaky causing a PLC fault. Some faults require the RSLogix software to reset them. Others can be reset by cycling power, I believe this is one of them. Without the software, you're kind of flying blind.

Brad Waybright

The more you know, the more you know you don't know.
 
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Thanks for the replies. I did remove all the modules and put them back with no success.
There is a devicenet module displaying 0080, see pic, and I assumed that this was an error message for the plc (it says address/error above it) but I think I was mistaken. So I have now got a programming lead and a laptop with the RSlogix software and see if I can find out what is going on.
 
 https://files.engineering.com/getfile.aspx?folder=66c7fe2c-c686-4e95-a640-3650b239ebe7&file=IMG_20210225_145551.jpg
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Looking at the picture its seems the bus and the units are OK , not shore if this is the right manual but if it is
it seems that the CPU isn't in RUN which I also can se at on the picture that it isn't.


Chapter 8
80 In Idle Mode Module is in Idle mode.
Put the controller into RUN mode and enable the RUN bit in the Module Command Array. See
page 16.

Best Regards A

“Logic will get you from A to Z; imagination will get you everywhere.“
Albert Einstein
 
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Thanks A, think it is the right manual. The mode switch is in the run position and it initially runs then stops. Having to wait a week now before I can get back onto the ride with a laptop.
 
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You are welcome :-)

Best Regards Anna

“Logic will get you from A to Z; imagination will get you everywhere.“
Albert Einstein
 
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If that's a Devicenet card that is showing the error, chances are its a terminator problem on that bus, rather than PLC or backplane.
Devicenet is an extension of CANBus, which needs terminator resistors at both ends of the bus (across CAN-H & CAN-L if I remember correctly). I'm not familiar enough with the AB products to know if there's an option or a switch that does the local end termination.
The other possibility of course, is that the bus has become broken somewhere and the section with the terminator on the other end is no longer connected.

EDMS Australia
 
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UKpete said:
The mode switch is in the run position and it initially runs then stops.
Click to expand...

May have lost the program. Do you have an electronic copy?
 
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Once you get into the processor, I think you'll find that the PLC fault has nothing to do with the devicenet error. Code 80 indicates the module is in idle status, which would be the normal state if the PLC isn't in run mode.

Brad Waybright

The more you know, the more you know you don't know.
 
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Yes Brad I think you are right, I'm slowly going up the learning curve. djs - we do have an electronic copy, as soon as I can get on the ride I can try reinstalling failing all else.
Thanks for the replies folks
 
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UKpete--
Curiously wondering if there's any progress?

Brad Waybright

The more you know, the more you know you don't know.
 
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Hi Brad
Yes and no (but mainly no). We did get plugged in using RSLinx Classic and learned that one of the adjacent i/o modules was faulty, when we eventually got a replacement we found that the plc now runs (run light on, no fault light) although the ride still doesn't operate due to unexpected plc outputs. I'm due to go back on Tuesday for another look, and will post any progress.
Peter
 
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If you have devicenet drives or other devices, and you still show an error on that module, I would expect things to be wonky.

Brad Waybright

The more you know, the more you know you don't know.
 
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