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Problem using module 6ES7 231-5QD30-0XB0 (PLC S7-1200)

Created by: shmaxx at: 11/23/2011 1:18 PM (6 Replies)

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11/23/2011 1:18 PM	Rate (0)
shmaxx Regular Member Joined: 11/23/2011 Last visit: 2/18/2021 Posts: 4 Rating: (0)	Dear Sirs, We apply module 6ES7 231-5QD30-0XB0 for controll of bell-type furnace in sheet-rolling shop and we have a big problem using module 6ES7 231-5QD30-0XB0 (controled by CPU 6ES7 212-1BD30-2XB0) Using temperature-compensated cabel the thermocouples type K are connected directly to the module. Length of the path max 10 meters. Sometimes all 4 chanels has failure. The reason why it is happens on 8 identical technological equipment we can’t understand. In real as we suggest failure has one or two chanel (indication from PIW +-32768 that means overflow), but another chanels has incorrect indications (not overflow, but not correspond to the facts). Diagnostic buffer of CPU has message - "Low (High) limit violated" with indicated adress of PIW. Cheking of all thermocouples confirms the correct operation of its. Separattelly disconnection of thermocouple is not help, after disconnection of all thermocouple we can see green light of CPU и AI*TC light-emitting diodes. After reconnection at least one thermocouple to the any chanel we have the same failure. Restart (by voltage supply) of PLC solve this problem (restart by programm not). After this operation there is no any failure in diagnostic buffer, all 4 chanles has correct indication with the same thermocouple. Thanks in advance to any advice. Best regards, Maxim.

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11/23/2011 1:52 PM	Rate (0)
Marko Bursic Platinum Member Joined: 9/8/2009 Last visit: 12/13/2020 Posts: 1387 Rating: (136)	I am not very expert inTCs, but in manual is some data that I connected together. TC module is galvanicaly isolated to backplane - field to logic isolation, but channels are not isolated in between them. The other detail you will find is that you have to use floating type thermocouple - it means the tip of thermocouple doesnt touch the metallic body -isolated. maybe you have wroung type of TCs. If you use only one than it doesnt matter, but if you connect just one the ground current begins to flowfromone channel to other.

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11/23/2011 2:19 PM	Rate (0)
LarryAm Bronze Member Joined: 9/19/2011 Last visit: 2/18/2021 Posts: 119 Rating: (32)	What version of firmware do you have in the 231-5QD30 module? If you do not have V01.00.05 then see this link to upgrade. https://support.automation.siemens.com/WW/llisapi.dll?func=cslib.csinfo&nodeid0=41886031&nav0=tree&lang=en&siteid=csius&aktprim=0&extranet=standard&viewreg=WW&objid=41885258&treeLang=en This should fix the problem that you are seeing.

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11/23/2011 6:06 PM	Rate (0)
4tm Regular Member Joined: 9/21/2010 Last visit: 11/16/2020 Posts: 1 Rating: (0)	make sure that you ground the module and connect the M of the 24V Supply to the same ground instruction sheet for module should provide additional details

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11/24/2011 11:33 AM	Rate (0)
shmaxx Regular Member Joined: 11/23/2011 Last visit: 2/18/2021 Posts: 4 Rating: (0)	Thank you all for your answerers! Upgrading of the CPU and AI * TC operating system the we have made, unfortunately it was useless. Grounding of the module and power supply is correct. Now we check the operation of the grounding circuit.

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11/24/2011 1:09 PM	Rate (0)
Marko Bursic Platinum Member Joined: 9/8/2009 Last visit: 12/13/2020 Posts: 1387 Rating: (136)	Have you measured TCs too see if they are floating type or they are grounded?

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11/28/2011 3:26 PM	Rate (0)
0_Einstein Diamond Expert Joined: 7/7/2010 Last visit: 2/25/2021 Posts: 10152 Rating: (1687)	If you connect one of the TCs (with nothing else connected) to one of the TC modules directly at the module, do you findeach channel work properly? If so, what happens if you use a short piece of that sameK-Type cable and connect up to that same working TC at each of those inputs? How about if you add another TC? Does it only fail once you connect the TCs into their housing in the furnace? You will need to step through the problem to isolate the problem. I've used plenty of K & J type TCs and they all work fantastically, reading within 0.5C without calibration using internal reference. Maybe a screen shot of one of the TC input configuration screens might help.
	science guy
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