CompactLogix L35E (16.3) MAJOR ISSUES

[phuz 2]

I have a CompactLogix rack with the L35E processor, two High Speed Counter cards, two thermocouple cards, an analog input card, an analog output card, digital in, and digital out. I am now having an issue that I am completely unable to troubleshoot. Aside from the headache I have from trying to configure these high speed counter cards to give me the RPM value desired, I tried to do a download to the controller, and the I/O was "OK" before hand. Right after it downloads, the I/O goes to Not Responding, and the processor stays in Program Mode. I can change it to Run Mode, and the I/O Not Responding stays the same. However, when I try to go back to program mode, it gives me the error: "The controller acknowledged your request for a transition to Program Mode, but it has not completed the transition." All my I/O has the nice yellow triangle complementing it, including the CompactBus Local, which states connection timed out. Some of the modules say "Shutting Down" and some say "waiting." In order to get the thing back, I have to power-down the whole rack, bring it back up, clear the fault....and I'm right back at square one...unable to successfully complete a download with I/O OK. The download is doing something to the controller, obviously. On a similar issue, when we press E-Stop on the panel, it shuts off all the I/O, but leaves power to the controller. After a brief period of time without the I/O responding, the controller will fault, which is undesired outcome for us. Any way to prevent this?

[jstolaruk 9]

My first thought is to make sure everything in the system (in this case just the processor I believe) to the latest firmware that my ControlLogix s/w would support. Can't really comment on your E-stop problems unless you post the electrical drawings to start with. Edited 17 Oct 2008 by jstolaruk

[Ken Roach 194]

You might have a power distribution problem from the power supply to the I/O modules if you have the smaller 1769-PA2 or -PB2 power supply and all the I/O is to the right of the power supply. Post the exact part numbers and their locations and folks can doublecheck the power budget. I use Integrated Architecture Builder but the user manual has all that data too. A general layout check: Is there just one power supply, and is there a 1769-ECR terminating end cap securely installed ? One reason I've seen for controllers to fail to transition to Program Mode is that they're busy with an overloaded communication buffer. Sometimes it's because of bad MSG instruction logic, but I expect it is possible for a backplane full of incomplete connection messages to cause the same effect. CompactLogix shouldn't fault when I/O power is removed. :headscratch: If you can remain online with the controller, check the Major Fault code to see if it is related to a particular slot number.

[phuz 2]

Here is a snapshot of my I/O config. I have slot 3 inhibited because the IO is physically not installed yet (I made that addition this morning). The power supply is a 1769-PA4, and is located between slots 3 and 4. There is a terminating end cap, yes. There are no messaging instructions or block transfers tacking place. After speaking with Rockwell last night, analog IO will cause the processor to fault if power is removed from the card, so all I have to do is remove the checkbox in the card configuration that tells the controller to fault if the card faults....so hopefully that solves that problem. Edited 17 Oct 2008 by phuz

[TimWilborne 108]

I think there might have been a misunderstanding here. It is not unusual for me to use a control power relay to turn off power to my external sensors, including the 24VDC to my analog cards and haven't had problems with them faulting. You might want to call Rockwell again and verify this is true. I think fixing the slot addressing will solve the problem

[Ken Roach 194]

TW is right; the 1769 bus assigns slot numbers left to right as they are connected. If you need to "reserve" a slot, you need to use the 1769-ARM address reserve module. The 1769-IT6 module in Slot 4 might correctly connect, since it has the right ID (from Slot 5) but all the others should have identity failures. Check the fault codes for the failed I/O connections and see if they have to do with identity instead of connection timeout.