See this document to use the DMM connector on the molbox1 or molbox1+ flow terminal with the MFC option. This might be used to connect a reference DMM with better uncertainty in voltage than the MFC option on the molbox1 or molbox1+ terminal.
The DMM connector always outputs volts (never current).
When a MFC profile in volts is used, the measured voltage is a direct reading from the corresponding pins on the 25-pin MFC connector.
When a MFC profile in current is used, the measured voltage is the current from the corresponding pins on the 25-pin MFC connector that is run through a 250 ohm (±0.01%) resistor on the MFC board inside the molbox1 or molbox1+ terminal. The resistance of this resistor can be measured on pins 1 to 4 of J3 on the MFC board if desired.