This unit is used witth the Controller to provide convenient front panel imputs.There are banana jacks for two voltage inputs, one of wich has a switch providing three scales: 5,15, and 40V.
A DA9S connector accepts properly-formatted RS-232 inputs
Also on its front panel is a Secure Digital Module socket for recording.
It also has a rechargable battery which powers both units, when it is switched in parallel with the power jack on the rear of the Controller. It is recharged by connecting a supply of 13-16 V to that jack.
Here are the circuit diagrams
Here is the code