5/28/2014 10:39 AM | |
Joined: 1/23/2012 Last visit: 3/29/2024 Posts: 31 Rating: (0) |
Thanks to Mrhuggy_d1and MrNathanT, Its more useful for me your both of comments, But is it possible to read the same temperature from all the 4 channels without difference? if yes, please let me know, Because here our application is for furnace, so they need more accuracy. Please see the attached pic, if i did the grounding as mentioned in the pic, Can i read temperature without any difference from all the 4 channels? Regards, V.Arunram |
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5/28/2014 2:37 PM | |
Joined: 7/7/2010 Last visit: 9/20/2024 Posts: 15213 Rating: (2417)
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I have used many of the S7-1200 TC modules. I have never grounded a TC terminal as that would create another galvanic reaction on one of the ends of your grounded terminal. If you choose the same wire type as your TC wire needs, your ground connection will get galvanic voltage at the M terminal and be sensed at all your TC inputs, generating an error. Each TC cable should match your TC, and your inputs will read per the TC module specifications and the TC itself will react within its specifications, so overall, the best you will get without proper calibration is the default of around +/- 1 deg. If you have a TC simulator/stimulator, you can connect into your TC module as close as possible to where the TC is installed, simulate a calibrated signal, and then calibrate your TC input signal and get within +/- 0.1 to 0.2 deg which is much better, and will also make all channels read correctly. Be sure and put a jumper across any unused TC inputs. It will read something close to room or enclosure temperature, and not cause any odd behavior with other TC Channels - and if you use TC input monitoring, keep your module from showing RED blinking LEDs and keep the PLC from showing the MAINT LED. If you do not have a calibrated source, you will want to get one. |
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