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AI523 + PT100 + Temperature reading error (offset -8 C)
Good Morning ABB,
I have a problem with my PT100 readings.
I am using AI523 and 3-wire PT100 sensors wired and configured as 2 wire PT100 sensor(configuration (Capture) and wiring diagram in the attachment).
The readings are very weird, they are offset around -12C on TT005/TT016/TT031 and -8C on TT006/TT022/TT042, however TT052 works completely fine (Capture 3).
In the situation from the attachment TT005 and TT006 should show exactly the same value around 20C. Same thing applies to TT016/TT022 around 30C and TT031/TT042 around 190C.
I have tested the temperature probe (TT016) and it is giving me correct resistance for the ambient temperature I have. Then I have tested it on AI531 input module and it works fine on the PLC side as well.
The test were conducted on the test bench on my desk, the faulty reading probes are placed on the factory site in different environment.
My conclusion is that there might be some interference based on cable resistance on the way from the probe to the cabinet, but I have never seen an error going down with the temperature.
The other option is that the module is damaged in someway, however only the 1.0 to 2.9 side. Is that really possible ?
Do you have any other suggestions ? Maybe I am missing something.
Regards,
Rafal
I have a problem with my PT100 readings.
I am using AI523 and 3-wire PT100 sensors wired and configured as 2 wire PT100 sensor(configuration (Capture) and wiring diagram in the attachment).
The readings are very weird, they are offset around -12C on TT005/TT016/TT031 and -8C on TT006/TT022/TT042, however TT052 works completely fine (Capture 3).
In the situation from the attachment TT005 and TT006 should show exactly the same value around 20C. Same thing applies to TT016/TT022 around 30C and TT031/TT042 around 190C.
I have tested the temperature probe (TT016) and it is giving me correct resistance for the ambient temperature I have. Then I have tested it on AI531 input module and it works fine on the PLC side as well.
The test were conducted on the test bench on my desk, the faulty reading probes are placed on the factory site in different environment.
My conclusion is that there might be some interference based on cable resistance on the way from the probe to the cabinet, but I have never seen an error going down with the temperature.
The other option is that the module is damaged in someway, however only the 1.0 to 2.9 side. Is that really possible ?
Do you have any other suggestions ? Maybe I am missing something.
Regards,
Rafal
