Figure 6-30 2-wire RS-485 connection 
 
For a 2-wire RS-485 connection the Tx+ and Tx- 
terminals must be connected, while the Rx+ and Rx- 
terminals may remain unconnected (no need for jumpers). 
 
 
 
Figure 6-31 4-wire RS-485 connection 
 
 RS-485 connections need terminating resistors to 
reduce voltage reflections that can cause the receiver to 
misread the logic level. 
Proving signals 
The connection of the prover signals depends on the Spirit
IT
 
Flow-X type and the prover set-up. 
 
Flow-X/P 
Ball prover / Compact prover 
 Connect the flow pulse signals to the corresponding modules 
 Connect all detector signals to all run modules 
 All applicable prove signals (except the detector signals) may 
be distributed over the available modules (they only have to be 
connected once):  
–  prover pressure(s) 
–  prover temperature(s) 
–  prover densitometer 
–  4-way valve commands and statuses 
–  prover commands and statuses 
 
Master meter proving based on pulses 
 Connect the flow pulse signals to the corresponding run 
module(s) and master meter module 
 Connect a digital output of the “Master Meter” module to a 
digital input (prove detector in) of itself and all run modules 
 
Master meter proving based on totals 
 No connections to be made (except from the pulse inputs in 
case of pulse meters) 
 
X/P 
Ball / Compact prover 
 
Figure  6-32:  Proving  with  a  ball  or  compact  prover  on  an  X/P  flow 
computer.