How to wire a 3-wire pressure transmitter to a AI845 module
My client has an application where they have three pressure transmitters that need to get wired to a AI845 module that has a TU810V1 base. The transmitter has the following wiring diagram. Where pin 1 is +24VDC, pin 2 is 4-20mA, and pin 3 is the 0VDC.
Looking at the wiring diagram for the TU810 and AI845 I believe you need to have an external 24VDC power supply to power the instrument and the signal wire from pin 2 will land on B1 and pin 3 lands on A1 if you use the 24VDC power supply that is wired to AI845 module. Can a separate 24VDC power supply be used to power the instrument and still wire the 4-20mA signal to the analogue card?
In case you want to use other 24VDC power supply module for the instrument, than the one for the system, then the connection should be the following:
+24VDC of the external power supply to pin 1
0VDC of the external power supply to L- terminal (both power supply modules need to have a common -)
pin 2 to the desired Bx terminal (e.g. B1)
pin 3 to the corresponding Ax terminal (e.g. A1) - terminals Ax are internally connected to L-.
PLC's power supply +24VDC and 0VDC have to be connected to L+ and L- terminals of TU810 as well