The on-site flowmeter totalizer is displaying abnormally
Thread Content
This post was last edited by Catalyzing a Grain on 2018-7-14 at 17:41. The equipment on site is provided by the raw material supplier, and only basic control is needed. The on-site flow meter’s local indicator was showing normal readings. However, due to production requirements, it was necessary to conduct flow measurements in the DCS control room. After a branch was taken from the output terminal of the on-site flow meter and sent to the DCS, the meter continued to display a minimum value of -1.2 L/M; no alarm was triggered, and the readings appeared normal. It’s a Yokogawa flow meter – I’m seeking advice: could it be that the load on the output terminal of the flow meter was exceeded as a result of having two connections?
It is likely due to an excessive load on the flow meter; it is recommended to use a one-in-two-out signal distributor.
Does it mean connecting a wire directly to the 4-20mA output terminal? You can’t handle signal lines like that; you need a 1-to-2 signal splitter.
The second floor is the correct choice; the most stable option is a transmitter module with one input and two outputs. If the instrument supports communication protocols such as Modbus, communication can also be used for this purpose.
It is caused by the insufficient load capacity of the flow meter; the usual solution is to add a signal distributor.
It is preferred to use the flow meter’s communication output to connect to the DCS; if the flow meter does not support such communication output, then an isolated distributor or safety barrier with one input and two outputs can be used. However, over time this can lead to discrepancies between the cumulative flow values displayed by the DCS and those from the field flow meter.
When connecting I/O, pay attention to whether it is active or passive. Can they also be connected in series?
The 4-20mA signals need to be connected in series. It is necessary to check whether Yokogawa’s output terminals are active or passive, and the same should be done at the DCS side. If the configuration is not appropriate, there will definitely be no indication
Flow integrators can generally be equipped with a 4–20 mA signal output