You can assign PWM-controlled devices which are connected directly to one of these mega2560 controller pins - from 2 to 13, and 44,45,46. In the Configurator, select the needed parameter for output and select one of these free pin.
Connect an ammeter to the PWM output of the controller through a current limiting resistor, with the other wire of the gauge connected to the ground. The resistor can be varied from 5 to 100 kOhm depending on the gauge you will use. You can select a suitable resistors by checking the range of the gauge needle. The simplest option you can use just one limiting resistor. Here are the connection options of the coil gauge:
You can use one 24-channel PWM driver (TLC5947) with CLK signal connected to one of these mega2560 controller pins: 30 - 37.
To "connect" the TLC5947 driver in the configurator, click one pin to which the CLK signal of the PWM driver will be connected (pins #30-37) and select "PWM Driver" in the "Assign extemsion" window. Two other control signals are connected to corresponding D and L signals of the system bus. +V is the driver powering input, you can either use +5v from the bus or connect another external power supply.
In this case when choosing a parametr for output in the Configurator, you need to select the PWM controller output number (one of 24 outputs).
Unlike direct connection, the gauge's "+" output is connected to +5V, and "-" is connected to the signal, not to GND.
To assign any specific parameter for output to the gauge, find this parameter in the configurator database and select it for PWM output (either directly connected to the pin, or to any of 24 PWM driver output).
Before using the moving-coil gauge in your cockpit you need to calibrate it. Use the convenient Calibration Tool in the SimVim plugin to correctly map the data value range on the gauge dial.