Seeking help with module contact issues in Allen-Bradley DCS systems
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The company has a newly purchased electromagnetic flowmeter. When the feedback signal is connected to the corresponding terminals of the FM148C, no flow rate is displayed on the DCS, but the flow rate is shown on the gauge at the site. When measured with a multimeter at the module terminals, the input current signal was found to be 38 mA. What could be the reason for this?
Does the DCS terminal board have power distribution? Disable current signal distribution function
Should we try removing the wire and checking the current at the current signal output terminal of the electromagnetic flowmeter? Is it possible that your 4-20mA output line is active, causing the flow meter communication module to be damaged?
Your electromagnetic flowmeter should be a four-wire instrument, and Hilscher’s terminal blocks should be passive. 38MA should be connected to the active section.
For four-wire systems, if it is a Beckhoff safety barrier, it needs to be connected to 89; the card should be connected to 14
The electromagnetic flow meter is working fine; it outputs a current of 8.5 mA. When the signal wire is connected to the corresponding terminal on the module, the current rises to around 30 mA, but it drops back to 8.5 mA once the wire is disconnected. The problem must lie either in the module or in the base. However, trying several different modules didn’t change anything – this flow meter uses a 2-wire output system. I don’t get it
The output current of the electromagnetic flowmeter is 4-20MA, but the actual output current is 38MA – this higher current can be attributed to two reasons: either the voltage is too high or the resistance is too low. In this case, it’s likely that the voltage is too high. It’s possible that your electromagnetic flowmeter has an active output, and so does your card; when connected together, the voltage exceeds 24V. It is recommended that you measure the voltage – it’s definitely above 24V. In such a situation, you should use a passive card. If it’s connected to a Siemens DCS system, then you need to replace the input terminals of the safety barrier. Please measure to see whether those terminals are connected without any voltage applied, and give it a try