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Why can't I get a 4-20mA signal out of a Momentum 170AAO92100 analog output module when using an ohmmeter as the load?

Goals and Symptoms

Why can't I get a 4-20mA signal out of a Momentum 170AAO92100 analog output module when measuring across the output channels with a meter?

Causes and Fixes

Since the 170AAO92100 module has a load impedance specification of 600 ohms maximum for 4-20mA, usually a meter cannot be used to verify current output due to its high impedance. Therefore, it is recommended to wire a 250 ohm load resistor across the channel and measure voltage across it. The voltage should vary 1-5vdc corresponding to 4-20mA. Alternatively, if there is an existing analog input card with a spare 4-20mA channel, then the analog output can be wired to the analog input to verify the correct current output of the 170AAO92100.


Legacy KB System (APS) Data: RESL191675 V1.0, Originally authored by DaSo on 08/08/2008, Last Edited by DaSo on 08/08/2008
Related ranges: Modicon Momentum I/O
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