Regarding thermal resistors
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One thermal resistor shows the correct resistance value when measured on-site, and the resistance value is also correct when measured at the back of the cabinet; however, the DCS does not display any values. When a resistance box is connected to the cabinet, normal readings are obtained. Please analyze the reason for this
You’d better describe the malfunction in more detail. On-site measurement? Measured at the Ohm cabinet terminal? Measure with an ohm resistor box? Is Ohm 3-wire or 4-wire? Is the wiring correct? Are the terminals functioning properly?
To put it clearly, only in this way can everyone help you analyze the reasons; for example, measuring resistance on-site – what system is being used?
There’s no problem with the channels or the resistors; it’s the wires that are the issue – I need to check them
Try replacing the DCS card... According to your description, there are no issues with the thermal resistors on site or with the wiring; yet the computer doesn’t display any data. It’s likely that there’s a problem with the DCS card.
Connecting a resistance box to the card shows normal operation
According to you, there’s nothing wrong with your thermistor. If the resistance value shown by the resistance meter is normal when it’s connected directly to the card, then that means the card is also fine. After ruling out those possibilities, the only remaining issue could be the wiring. Please check carefully whether there are any problems with your wiring, and make sure that the three-wire or four-wire configuration is correct. If it’s a three-wire system, verify that all three wires are connected properly; it must be a wiring issue.
Is the DCS wiring incorrect? Also, the thermal resistor requires a dedicated holder
Regarding your question, it’s certain that the on-site part is fine. So you can ignore that aspect and check whether the cards and channels are working properly. It’s also possible that the DCS personnel were negligent and failed to configure this element.