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limited span due to coarse sensor

Created by: Hammondyngve at: 9/16/2019 10:07 AM (26 Replies)

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9/16/2019 10:07 AM	Rate (0)
Hammondyngve Posts: 16 Rating: (0)	Hello everyone! I am a newbie to programming, although I know the basics after studying PLC in my automation studies. I have a problem, and I am about to start hurting myself. I have a LOGO. I have a 0-250mbar pressure sensor. What i do NOT have is the calibration unit for the sensor. (IFM PL2058) I have Soft Comfort 8.2. The sensor is not the right kind, it is far to coarse. There is nothing I can do about that with the tight budget I am on. It reads between 3,69 mA and 5,49 mA in the area I want to use it. I have a LOGO without display, and a LOGO! TDE display. I have made a working program, but when I try to adapt the sensor's limitied span into the LOGO! program, I run into trouble. I would like for these 3,69-5,49 mA to show as a 0-100 % bar graph (only bar, no numbers), since I need to be able to change a setpoint for when to stop a pump and open a valve. I have now tried about every thing I know, and it still only reads my values (fed from a multimeter) an the span of 4-20mA. I hope I am making myself clear. Is there anyone out there who'd like to give me a Little advice or Point me in the right direction? Thanks so much in advance, Yngve
Hammondyngve Posts: 16 Rating: (0)
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9/16/2019 10:16 AM	Rate (0)
ixo65 Grandmaster-Expert Joined: 12/18/2014 Last visit: 1/16/2025 Posts: 34498 Rating: (4306)	Hello Hammondyngve, First of all, welcome to the forum. According to the data sheet, the sensor output signal is 4-20 mA. Therefore, the range can not be evaluated from 3.69 mA to 5.49 mA since 4 mA is the minimum. How do you get to 3.69 mA? Maybe you did not connect the sensor properly?

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9/16/2019 10:59 AM	Rate (0)
Hammondyngve Posts: 16 Rating: (0)	ixo65 Hello Hammondyngve, First of all, welcome to the forum. According to the data sheet, the sensor output signal is 4-20 mA. Therefore, the range can not be evaluated from 3.69 mA to 5.49 mA since 4 mA is the minimum. How do you get to 3.69 mA? Maybe you did not connect the sensor properly? Thank you very much. I have learned a lot already during my time sneaking around here. As to how I get 3,69 mA, my guess is as good as any. It may be a faulty sensor. I will double check my Connection. I just believed it was because the sensor is badly scaled. Also, it has been in storage for a while. Who knows, maybe it has taken a fall to the floor or something and is just simply broken. I connected it with 24 VDC: L+ to +, and L- to -. For the analog output I connected the remaining wire to + and L- to -. I may be totally wrong, I guess I have to check closer.. Thanks a lot for the answer! Very much appreciated! Yngve
Hammondyngve Posts: 16 Rating: (0)
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9/16/2019 11:08 AM	Rate (0)
ixo65 Grandmaster-Expert Joined: 12/18/2014 Last visit: 1/16/2025 Posts: 34498 Rating: (4306)	Is the voltage supply of the sensor the same as for the LOGO! ? How did you connect sensor? To the LOGO base module or to an analog acquisition module AM2? I need more information .... and as accurate as possible .....

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9/16/2019 11:41 AM	Rate (0)
Hammondyngve Posts: 16 Rating: (0)	But of course…:) The sensor is powered by the LOGO! Power supply, just as the PLC. And then connected to the input of an AM2. The AM 2 is connected to the LOGO 12/24RCEo by the built-in connector, and seems to work just fine. Feeding the input with 4-20mA from a Fluke 789 works like a charm.
Hammondyngve Posts: 16 Rating: (0)
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9/16/2019 12:07 PM	Rate (0)
ixo65 Grandmaster-Expert Joined: 12/18/2014 Last visit: 1/16/2025 Posts: 34498 Rating: (4306)	If everything was connected correctly, then it could not be that you measure significantly less than 4 mA. Which terminal of the AM2 exactly did you connect the sensor output? Connection 1 of the sensor to + 24 VDC. Connection 3 of the sensor to 0 VDC. Connection 2 of the sensor to the current analog input of the AM2 (I1 or I2). Connect the M-terminal of the analog input of the AM2 (M1 or M2) to 0 VDC of the power supply.

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9/16/2019 12:44 PM	Rate (0)
Hammondyngve Posts: 16 Rating: (0)	ixo65 If everything was connected correctly, then it could not be that you measure significantly less than 4 mA. Which terminal of the AM2 exactly did you connect the sensor output? Connection 1 of the sensor to + 24 VDC. Connection 3 of the sensor to 0 VDC. Connection 2 of the sensor to the current analog input of the AM2 (I1 or I2). Connect the M-terminal of the analog input of the AM2 (M1 or M2) to 0 VDC of the power supply. Connector 1: LOGO! Power's 24V+. Check. Connector 3: LOGO! Power's 0VDC. Check. Connector 2: I2 on the AM2. L+ and M- terminals on the top of the AM2 (the Power input) are connected to the LOGO! Power's 24V+ and 0VDC. M2 is connected directly to connector 3 (which also goes directly to LOGO! Power's 0VDC) with a jumper. I have connected both LOGO! plc and AM2 to ground with each their wire.
Hammondyngve Posts: 16 Rating: (0)
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9/16/2019 1:24 PM	Rate (0)
ixo65 Grandmaster-Expert Joined: 12/18/2014 Last visit: 1/16/2025 Posts: 34498 Rating: (4306)	Then is something wrong with the sensor.

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This contribution was helpful to 1 thankful Users Hammondyngve

9/16/2019 1:53 PM	Rate (0)
Hammondyngve Posts: 16 Rating: (0)	Faulty sensor.. Wow. I want to thank you so incredibly much for your help! It really meant the world today! Highly recommended from now on! Ordering new sensor, Yngve
Hammondyngve Posts: 16 Rating: (0)
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9/16/2019 2:00 PM	Rate (0)
ixo65 Grandmaster-Expert Joined: 12/18/2014 Last visit: 1/16/2025 Posts: 34498 Rating: (4306)	Have you tried the set the sensor on delivery status? Perhaps it may help.

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