I’ve got a problem and I’m stumped. Dealing with a Mitsubishi Q series. Q06H processor, two extension racks, a mix of I/O cards, GX-works2 software. The problem is with the analog output cards.
The analog output cards, both of them (model Q68DAIN), are giving me cropped outputs. The lowest point (should be 4mA) is 4.3mA on both cards, the high output (should be 20mA) is 13.0mA on one card, 9.0mA on the other card.
The weird part is up to the max output of 13 on one, 9 on the other, the mA almost matches what it should be (0-4000integer = 4-20mA)for the bottom half of the range, ie: 0 int gives us 4.3mA, 2000 int gives us 12.4ish (should be 12.0 mA), then anything above gets progressively closer to 13mA as a max, 4000 int gives us 13mA.
They worked fine the other day, only today they started giving us this problem, I am unsure when exactly during the day the issue started, but to note, we did have a power bump earlier in the day. So sometime after that. I wiped and formatted CPU, re-installed an earlier version. I am 100% convinced it is not the program or the switch settings in the software.
We replaced the backplane(Q612B), the extension rack's 5vdc power supply (Q61P) and both cards (Q68DAIN). Same problem. Nothing has changed in the field.
The Analog output cards require an external 24VDC source wired directly to the card, this 24VDC power supply also powers most of the instruments via loop power. The power supply is delivering the rated 24VDC.
I have disconnected all the instruments from the 24VDC, using the supply to power only the two analog output cards, disconnected all the analog output field wiring from the terminal strips and the problem still persists.
It seems the issue is not the PLC hardware (it has been replaced), it is not the field wiring, it is not the software or program. It seems issue is in the panel and the marshaling.
I am out of ideas. Has anyone encountered a problem like this before? or have any ideas where to point the finger?
*** one other thing to mention:
There is a debugging tool that allows you to view the buffer data from the analog output card, I can see that 4000 int is indeed being written into the buffer for the output. So it is definitely not a scaling issue from the software, nor an issue with the CPU's ability to write to the card. This, coupled with the problem persisting with brand new components in place, re-enforces that the software and hardware is operating as it should.
The analog output cards, both of them (model Q68DAIN), are giving me cropped outputs. The lowest point (should be 4mA) is 4.3mA on both cards, the high output (should be 20mA) is 13.0mA on one card, 9.0mA on the other card.
The weird part is up to the max output of 13 on one, 9 on the other, the mA almost matches what it should be (0-4000integer = 4-20mA)for the bottom half of the range, ie: 0 int gives us 4.3mA, 2000 int gives us 12.4ish (should be 12.0 mA), then anything above gets progressively closer to 13mA as a max, 4000 int gives us 13mA.
They worked fine the other day, only today they started giving us this problem, I am unsure when exactly during the day the issue started, but to note, we did have a power bump earlier in the day. So sometime after that. I wiped and formatted CPU, re-installed an earlier version. I am 100% convinced it is not the program or the switch settings in the software.
We replaced the backplane(Q612B), the extension rack's 5vdc power supply (Q61P) and both cards (Q68DAIN). Same problem. Nothing has changed in the field.
The Analog output cards require an external 24VDC source wired directly to the card, this 24VDC power supply also powers most of the instruments via loop power. The power supply is delivering the rated 24VDC.
I have disconnected all the instruments from the 24VDC, using the supply to power only the two analog output cards, disconnected all the analog output field wiring from the terminal strips and the problem still persists.
It seems the issue is not the PLC hardware (it has been replaced), it is not the field wiring, it is not the software or program. It seems issue is in the panel and the marshaling.
I am out of ideas. Has anyone encountered a problem like this before? or have any ideas where to point the finger?
*** one other thing to mention:
There is a debugging tool that allows you to view the buffer data from the analog output card, I can see that 4000 int is indeed being written into the buffer for the output. So it is definitely not a scaling issue from the software, nor an issue with the CPU's ability to write to the card. This, coupled with the problem persisting with brand new components in place, re-enforces that the software and hardware is operating as it should.
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