The temperature-dependent output of the Rosemount 644 is always 21mA
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This post was last edited by zhengmessage on 2018-10-28 at 17:56. A 644 temperature sensor was replaced on-site, and after the replacement it always displayed 110°C (with a range of 0–100°C). After entering 475, checking the overview shows that the temperature is 27°C, which is normal, but the current output value is 21mA. Upon testing, it was found that the thermometer was functioning properly and the DCS channels were also normal; however, the output corresponding to temperature changes did not change, showing a false value of 21mA continuously. (The temperature change means that even when the temperature is not connected, it still shows 21mA.) Does anyone know what’s causing this? I see someone posted a question before, but there was no answer; others said that another sensor channel needs to be blocked? Does it work? I see that there is indeed a message on the 475 indicating something like a sensor 2 alarm. How to operate the shield channel on 475 HART? Which menu? Thank you!
The 644 model you chose supports two sensors, right? If you specify sensor 2, that’s usually the case. Can’t you simply disable sensor 2 in the configuration menu?
This is the type being used – a temperature-sensitive module. How do I operate it in shielded mode? It’s not available in 475
Is it still showing 475 right now? Take a screenshot of the configuration interface to take a look
The temperature control unit has been taken back inside the house for testing, but since it’s now time to leave work, I can only wait until tomorrow\ud83d\ude05
The one you ordered is designed to hold two units, but is it actually being used with just one unit, or is the other one broken?
In practice, only one is used (on one side, for wiring)
Is there an error in the sensor type configuration? With thermal resistors, the issue lies in the wiring; with thermocouples, it’s the model that matters. The second sensor is a temperature sensor built into the temperature-sensitive element; it is used for cold-junction compensation when thermocouples are employed, while it is not necessary when thermal resistors are used.
I’m also suspecting a configuration issue now, but I’ll just set the wiring type and range and change the tag number; I’m not too familiar with the rest.
Just set it to not use in configuration>manual setup>sensor2