baefam

FX2N 64MR and Fx2n 4AD temperature error

9 posts in this topic

Hello I'm new and not a PLC specialist. This is for Dry Clean machine control PLC. Getting temperature error on dry cycle. 5 to 35 Centigrade is working range and actual temperature is 22 C. It's just normal. Temperature display indicates 21 C but gets error message of temperature is under 5 C. System component and Flow of signal is as follows. PT100 #1, there is total of 4 of PT100 rest of three works fine FX0n 16EYR, seems to be switching plc. three PT 100 connected to here. sample datas in sequence and send signal to SL-RTD (sinwoo escon) SL-RTD(a), convert resistance to dc, FX2N 4ad, There is two SL-RTD and both connected to FX2N 4AD on separate channel FX2n 64MR, Control PLC. displays error. I tested some different ways. I put new FX2N 64MR but happens same Swapped line with other PT100 and probe seems to be fine. I did test, Heated up probe with heat, slowly changes and goes up from 22 to 35 C (but actual Temp is about 30 degree higher than display). After 35 C, number changes to 0 C and keep goes up again. from 0 C, Low Temp under 5 C error disappears and machine works fine around 10-20 minutes later, temp keep goes up and gets error message again at 45 C, High Temp over 35 C. (at this point Actual Temp is close to 100 C) my question is which part I have to replace. I feel FX2N 4AD went bad. do I need reprogram or replace with new ? Who should I contact to solve ? I'm at Oxnard Ca, Near Los Angeles. Thank you .

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It is a bit hard to follow your "written schematics", do you think you could make a handmade drawing and scan it to your computer, then post it to display all the different connections in your setup? At first it sound like one of your channels is broken, but I'm not sure what you mean by SL-RTD... Is the SL-RTD a converter from PT100 -> Analog signals, or is it the other way around? And the FX0N 16EYR is a digital output module so I don't think that one has anything to do with this. The temperature in the display is probably not the same temperature that gives an error in this case. Since you have multiple PT100's there might be a different sensor that gives the error in the PLC (and the error is forwarded to the alarm list in the display)... But as mentioned, if possible please make a small drawing and post it.

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Thank you for your kind advise. I'm attaching files Thank you

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Perfect, But there is something not correct: The FX0N-16EYR is an extension module for the main PLC, and it is a digital output extension module - you cannot connect any kind of inputs (analog/temp/digital input) to it at all, so please check out this first. When it comes to the temperatures; did you measure the VDC signal going into the FX2N-4AD? Are you sure that it is one of the PLC components, or could it be the SL-RTD's? There should be a form of scaling so that e.g. 0-100deg.C = 0-10VDC or similar but check the SL-RTD's. Then check for correct/incorrect VDC from the SL-RTD's into the FX2N-4AD module.

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Hi Beafam, I agree with Kaare_T. What you also can do to check if the problem is inside the PLC or in the PT100 temp converter is to use a simulator and put 0-10Vdc to the input of the PLC card. If this signal is linear going up and down as you vary the voltage you know that the PT100 to DC converter went bad. (Mind the plus and minus at the input of the PLC while testing) If you don't have a simulator you cabn use a regulated power supply 0-10Vdc as well. Good luck, Theo V.

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Thank you everyone. I took your advise to measure input voltage of FX2N 4AD. It was around 4 VDC at room temperature. Should be around 2 VDC. I checked RTD reduced gain. I think over 10 years time, Gain had been changed it self. I might need new RTD (seems to be resistance to DC). Machine is working as should be and appreciate to all. Best regards. Chaang

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I think I need new Temperature converter, I found one of Phoenix, MCR PT100/U 28 10 34 0 which is 0-100' C, Power 24 VDC output 0-10 vdc. Only difference is voltage output VS original is Current output of 4-20 MADC. Is there any problem to replace ?. My machine doesn't need high precision control. Thank you

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Hi Baefam, If the existing converter was 4-20mA I should go for the same signal again by using a Phoenix MCR-PT100-I (part nr: 2810353) This way you don't need to change anything inside the PLC program. Using milli Amps signals is always prefered above voltage because of less EMC problems what can cause deviations in the output signal reading especially if you have no shielded cable and long cables running trough the same ducts as the mains power lines. If you take the Phoenix type MCR-PT100-U you need to change the input wireing to the PLC analogue module and do some new programming to your PLC. I think that you end up with more troubles than you have now. Best regards, Theo V.

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