Why is the temperature transmitter reading different from that shown on the main control unit?
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Excuse me, expert: we have a Siemens temperature transmitter there. Using the handheld controller, the temperature reads 152°C, and an multimeter shows a current of 12 mA. However, the computer displays 225°C – the computer’s measurement range is 300°C. What’s going on? Is it related to the PLC system?
Try switching channels to see if it can return to normal. Pass through the safety barrier or not? Check whether the safety barrier is functioning properly.
What problems could there be with Safe Shan?
If the safety barrier is of unreliable quality, there are no problems that it cannot cause – only those you can’t imagine. It’s best to go to the backend and take a look at the first-hand data obtained by the PLC, so as to be able to make an accurate judgment.
Well, I’ll go take a look tomorrow. Thanks!
The current is correct; it might be a problem with the computer’s software
If the range of the temperature relaxer is 300. So it outputs a 4-20MA signal. However, when the PLC receives 12MA, it displays 0-75%. The corresponding signal is 0-16MA. Check if there’s an error in the configuration? Does the safety barrier have a signal conversion function? I find it strange that the signal is an integer; it shouldn’t be due to a malfunction. It must be a setting issue somewhere.
If this happens suddenly with old equipment, check the AI interface board; if it’s new equipment, then check the program to see if it has been modified in some way.
It’s probably a coincidence that it shows 75%; it’s more likely that the AI made a mistake: lol
Measure the output voltage of the safety barrier, or perform a hot plug on the safety barrier
Generally, the readings from the local instruments do not match those from the DCS; in most cases, this is due to differences in the range settings on both sides. The range settings of the instruments and those of the DCS need to be made identical. Additionally, you can try marking the wire and checking the line current signal to see what value is received by the DCS. You'll find out by trying it.