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Using a 1734-IB8 to Count Flow Meter Pulses

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-I'm considering using an AB 1734-IB8 to count input pulses from a Micro Motion flow meter transmitter and, since I'm very new to this stuff, would like a little guidance as to how/if this can be done.

      My first concern is the wiring. The manual for the transmitter shows this wiring diagram for the specific model I'm using.


Here, B would represent the 1734-IB8 module. I'm not going to be using the analog loop. In addition to this wiring, terminals 9 & 10 on the transmitter will be wired to the same 24V and Common as my PLC modules. 

      The 1734-IB8 manual shows this diagram for wiring.


Should I consider the pulse output of the transmitter as a 3-wire device, connect terminal 3 of the transmitter to my 1734-IB8 input terminal and disregard the connection from terminal 4 of the transmitter, or should I just tie terminal 4 to my common?

Or, Should I consider my pulse output as a 2-wire device, tie terminal 3 of the transmitter to my 24V and terminal 4 to my input module?

My guess is the pulse output should be considered a 3-wire device with terminal 4 of the transmitter tied to my common, but I'd like a little bit of explanation with this.

-My second main concern has to do with the capability of the 1734-IB8 module to read pulses. More specifically, I would like to know what parameters of the module I need to research to see if it will be possible to read the pulses from my transmitter in the application I'm considering. If the 1734-IB8 can't be used, I would end up going to a high-speed counter card.




Edited by Jdeloz828

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The Terminal 3/4 pulse output is probably isolated from the MicroMotion transmitter power.   

Because your PLC and the MicroMotion are using the same main 24V power supply, the easiest thing to do would be to connect Terminal 4 to DC Common, thus tying the MicroMotion output to the same DC level as all the other devices.    Terminal 3 would then just connect to In0, In1, In2, In3, In4, or In5.     The POINT I/O's field power bus DC Common would also be tied to the same DC common as the MicroMotion and the POINT I/O adapter.

If you need to isolate that circuit, you can do so by using 1734-FPD field power distributor blocks.    In that case you would connect the MicroMotion Terminal 4 to DC Common on the field power bus, and connect Terminal 3 to an Input point.


The matter of pulse speed is probably more important.     POINT I/O is generally scanned by a CompactLogix or a 1734-AENT adapter, and those Requested Packet Interval (RPI) values can be relatively long compared to a pulse train.

What's the range of pulse outputs that the MicroMotion will be sending ?       My guess is that 1734-IK  (the 24V Counter module) is probably the best choice for a flowmeter input.


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Only needed to pick up a 33Hz pulse output. Wired it up how you specified using a 1734-IB4 and it worked great. Thanks for the help!

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