The Fluke 789 Process Calibrator and Meter; it's a combination of a 4 to 20-milliamp(mA) loop calibrator and a cat-4 to 600 volt (V) safety rated digital multimeter (DMM) with an oversized display.
In the milliamp function, the built in loop calibrator sources its four to twenty milliamp signal to test devices with a four to twenty amp input such as a PLCIO or analog milliamp indicators. The 789 also has a ramping function that allows you to ramp the milliamp signal into the indicator or other input device at one location and go to the device and check for an appropriate response such as a valve stem indicator change or mode indicator control system.
In milliamp output mode, you can manually change the milliamp output to verify the devices such as an input output to a PLC or a local indicator. You can go from zero to span and change the output in 25 percent steps, change the output in one tenth of a milliamp steps or one microamp steps for fine tuning.
The Fluke 789 Process Calibrator and Multimeter also has a 24 volt (V) loop power supply and will power a transmitter. You can simulataneously measure the miliamp signal drawn against the power supply. It also has a 250 volt HART resister you can switch in that will permit communication with a HART communicator.