signal lag
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The temperature of the thermal resistor is PT100. There is a mechanical thermometer on site. The control system is Siemens S-200 PLC. The temperature displayed on the system interface lags behind that displayed by the mechanical thermometer. How can the lag problem be solved? The distance between the thermal resistor of PT100 and the control system is 60 meters.
It cannot be solved because PLC's ability to process analog signals is inherently poor. But the lag time won't be too long, just a few seconds.
You should check whether there is any problem with the on-site thermal resistor installation position, or see if water has entered the casing. I think the problem should be found on-site. No matter how slow the system lags, it will only take a few seconds.
If the installation positions are similar, the temperature changes should be synchronous. Even if there is a lag, it will be at the time when the system interface is refreshed. The conversion of the signal to the PLC should be at the ms level, which can be approximately 1 second.； suggestion: 1. Check if there is any problem with PT100 ； 2. Check the refresh time of the system interface
Will it be better if we add on-site temperature changes?
The temperature display measured by the PLC will not lag for a long time. It is much faster than the temperature change itself. This may be because the heat source is close to the mechanical thermometer. If it is easy to change, it is recommended to change the installation positions of the PT100 and the mechanical thermometer.
PLC’s analog processing is inherently slow
1. If the PLC analog quantity refresh has time setting response adjustment, set the refresh time to be faster. If there is a host computer screen connected, the variable reading and screen refresh time needs to be set smaller.； 2. In terms of hardware, I don’t know what kind of PT100 package you are using. Try to choose one with a high response speed to the medium. Some galvanic packages (casings) will cause detection delays.
To what extent do you mean lag? 30s or a minute? It is recommended to check whether you have a special setting for the sampling period of this point when configuring at that time. It is mentioned above that water intrusion will affect the temperature measurement, but it seems that I have never heard of it causing signal lag!
It depends on how long the lag is. The PLC response is as slow as MS level. Finally, 1S can be considered. It should be 1. The problem of the on-site temperature measurement installation location, 2. PT100 installation problem, 3. PT100 selection or quality problem.