Every gauge/indicator in the overhead and MIP works slightly differently.
To connect the Phidgets voltage modules with Prosim I’m using my Phidegets2Prosim software
This is how I have interfaced them:

Overhead

EGT Temperature Indicator (N24 )

This indicator uses analog voltage -10v-+10v. For this I used a Phidgets Analog Voltage output module. Connect pin (1) to (GND) and pin (2) to (-/+10v)

Pin (D446)
1 - Coil Gnd
2 - Coil +
3 - 5v Backlight High
4 - 5v Backlight Gnd

Dual Pressure Indicator (N12)

This indicator uses analog voltage -10v/+10v for each needle. For this I used two Phidgets Analog Voltage output modules. It also requires 115v AV 400hz
Connect pin (3) to (-/+10v) and pin (4) to (Gnd). On the second module connect pin (5) to (-/+10v) and pin (6) to (Gnd)

Pins (D96)	
1 - 5v Backlight High
2 - 5v Backlight Gnd low
3 - Coil L +
4 - Coil L Gnd
5 - Coil R +
6 - Coil R Gnd
7 - Gnd
8 - 115v AC
9 - Gnd

Crew Oxygen Press Indicator (N20)

This indicator uses analog voltage 0-5v. For this I used a Phidgets Analog 4.2 Voltage output module. It’s the cheaper version of the 10/-10v module and works well here.
Connect pin (1) to (0-4.2v) and pin (2) to (Gnd)

Pins (D432)	
1 - Coil +
2 - Coil Gnd
3 - 5v Backlight High
4 - 5v Backlight Gnd Low

Cabin Temperature Indicator (N11)

For this indicator I wanted to show the flight deck real temperature. For this I used a temperature sensor.
You will need:
1 x RTD PT100 Temperature Sensor
1 x PT100 Temperature Sensor Transmitter (24V DC 0-10V 0℃ to 100℃)

The tiny screw terminal in the unit allows for fine-tuning the transmitter.

For the indicator:
Connect with a 7.5k Ohm resistor. Between pin (4) and GND. This will lower the voltage to a range the indicator can support from the 0-10v signal.
Connect pin (2) to the sensor 0-10v signal output

Pins (D90)	
2 - Signal input from temperature sensor transmitter
3 - Not used
4 - GND. Connect with a 7.5k Ohm resistor
5 - GND
6 - 5v Backlight Hi
7 - 5v Backlight GND low

MIP:

Flap Position Indicator (N54)

This indicator uses synchros. For this I used a LukTronics synchro Card. Straight forward using this card. It Requires 28V AC 400hz

Pin (D686)
 2 - 5v backlight GND Low
 4 - 5v backlight Hi
 5 -  Y (1) -> Ch 1
 6 -  X (1) -> Ch 0
 8 - HC (1) -> 28V AC
 9 - Z      -> Gnd
10 - HC (2) -> 28V AC
12 -  X (2) -> Ch 2
13 -  Y (2) -> Ch 3

Hydraulic Brake Pressure Indicator (N158)

This indicator uses current (amp) changes. A range from 4 to 20mA.
For this I used a 0~5v voltage to current converter, with a Phidgets Analog Voltage output module. Connect the converter (GND Input) to (Gnd) and the converter (VIN) to (5v) In the phidgets module..
From the converter (Out current) to pin (4) and (Out GND) to pin (5).

Pin (D2678)
1 - 5v Backlight Hi
2 - 5b Backlight GND Low
3 - 28V DC.
4 - Signal (4~20mA)
5 - Signal GND

Connect DC GND to converter

Interfacing OEM 737 Gauges / Indicators