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Variation in measured range by two different AI cards from same instrument

Created by: Kim A. at: 3/5/2013 6:56 PM (7 Replies)

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3/5/2013 6:56 PM	Rate (0)
Kim A. Posts: 7 Rating: (0)	I recently transfered four separate 4-20mA analog inputs from a module in a S7-400 rack (6ES7 431 1KF00 0AB0) to a module in an ET200S remote I/O rack... (6ES7 134 4GD00 0AB0). The ET200s Remote I/O is RIO, on Profinet, to the same S7 400 CPU as held the original analog input card. No changes were made to programming, except to change the peripheral address to the new location, and the instruments themselves were not re-configured.... The wires were simply cut, and moved to the inputs on the RIO module. Upon doing this, I noted that the digital values and the subsequently scaled values for these modules changed, on an order of aproximately 15%... the inputs to the RIO are reading about 15% lower than they were into the original AI module in the S7 400 rack. According to documentation for both of the modules in question, they both have the same measuring ranges... 0 to 27648, and are both 13 bit inputs. I therefore have to ask what else would cause this change in input value? Anybody have any ideas?
Kim A. Posts: 7 Rating: (0)
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3/5/2013 7:15 PM	Rate (0)
umencho Grandmaster Joined: 3/21/2006 Last visit: 1/10/2026 Posts: 10247 Rating: (1183)	Hello, Did you measure physically with multimeter the currents in both cases? In order to say the hardware connections (wiring) in both cases are according rules there? Best regards, Hristo Mihalev

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3/5/2013 7:38 PM	Rate (0)
Kim A. Posts: 7 Rating: (0)	Yes, the current measurement from the instruments were the same in both cases... The wires were actually shortened by a significant distance, (40 or 50 meters) so I would have expected the value to go up marginally, not decrease. Thanks.
Kim A. Posts: 7 Rating: (0)	Last edited by: Kim A. at: 3/5/2013 7:39 PM
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3/5/2013 9:18 PM	Rate (0)
umencho Grandmaster Joined: 3/21/2006 Last visit: 1/10/2026 Posts: 10247 Rating: (1183)	So, let's discuss the wiring there...what do you say?

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3/6/2013 8:35 AM	Rate (0)
Marcjan Diamond Member Joined: 4/22/2010 Last visit: 3/31/2025 Posts: 5697 Rating: (716)	UMENCHO So, let's discuss the wiring there...what do you say? And the sensors, what type you use? 2 wire? Regards, Marcjan
	Problem solved? Please let us know! Please no technical questions by PM, use the forum sections for your questions.
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3/6/2013 8:55 PM	Rate (0)
Kim A. Posts: 7 Rating: (0)	So yes, now we are getting down to the nitty gritty... The ET200s AI cards, you may have noted, are 2-wire, 13 bit, 4 inputs... The instruments are 4 wire devices... and they are wired as shown in the attachement. "Case 2". Attachment D:\tmp\upload\Case1Case2.pdf (518 Downloads)
Kim A. Posts: 7 Rating: (0)	Last edited by: CS Moderator at: 3/6/2013 10:56 PM Attachment reattached Last edited by: Kim A. at: 3/6/2013 8:56 PM
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3/7/2013 9:32 AM	Rate (0)
Marcjan Diamond Member Joined: 4/22/2010 Last visit: 3/31/2025 Posts: 5697 Rating: (716)	Hello, I was afraid off just that, that.s why i asked about the sensors. You need a 4wire card or a 2wire sensor. The old 400 card could handle both, the new et200 card not. Regards, Marcjan
	Last edited by: Marcjan at: 3/7/2013 8:10 PM Problem solved? Please let us know! Please no technical questions by PM, use the forum sections for your questions.
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3/7/2013 5:44 PM	Rate (0)
Kim A. Posts: 7 Rating: (0)	Thank you, Marcjan for your interest and response to my questions. Your help is very much appreciated. I will proceed accordingly. Kim A.
Kim A. Posts: 7 Rating: (0)
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