Field sensor signal conditioning

[Dave46]

Hi all we have a design using a Siemens S7-400, ET200M , S7-300 basically we have a bunch of analogue inputs, 4-20mA for water pressures, levels, temperatures, feeding into plc, same time there is a manual function override, with buttons/lamps that enables the operator to have control . on the panel will be stand alone controller, gauges for the operator to view, whilst in manual mode, so we need to take some of these analogue sensors to not only the plc but to source some of these manual components too, what is the best solution for this, signal conditioners for the sensors ? (whole site is on Profibus/Ethernet ) all help appreciated thanks

[DanW]

I'm not clear what you're trying to do. To "source [a field instrument] to a manual component" means? Does it mean that the pressure transmitter value which now runs to the PLC needs to be displayed at the instrument or somewhere else, somewhere else being ______ ? An example or two? Are all the instruments on Profibus, or are some 4-20mA? Assuming the instruments are Profibus and you need remote displays, an easy and cheap way is to buy an analog output card (0-20/4-20mA) and feed out each needed process variable as a current signal to a conventional panel meter mounted wherever it is needed. There are also loop powered meters for a location that doesn't have line power for the meter.

[Mickey]

My read is he wants to split the 4-20ma. See links below for a couple of options. http://www.miinet.co...sg_signal.shtml http://www.acromag.c...wered_Splitters Edited June 12, 2011 by Mickey

[Dave46]

hi thanks for replies both options would work, guess using the analogue output card would be cost effective to re-distribute these 4-20mA to stand alone gauges and controllers, lots of unknowns at this stage, is overseas project, not sure if having all sensors on profibus is option at minute thanks