contacts connect the source to the load so that connection caused transients are minimized the loop controller includes read write memory in which it stores program instructions and operational parameters so the source can readily change its feedback characteristics furthermore output voltage limits are readily imposed by software limits on the driver amplifier input voltage so no elaborate clamping circuitry at the output port of the source is necessary to prevent output voltage overshoot application_number US 84421286 A description fig1 illustrates a portion of a test system for testing electronic circuits this portion drives a port of a device under test dut with a predetermined voltage or current the dut is typically placed in a fixture not shown and placement of the dut into the fixture connects dut test nodes across force output terminals 10 and 12 for application of the desired voltage or current placement of the dut into the fixture also connects sense terminals 14 and 16 to appropriate dut nodes often the same nodes as those to which the force terminals 10 and 12 are connected when it is desired to drive the nodes to which the force terminals 10 and 12 are connected a host computer 18 that controls the entire test system sends signals along a bus 20 to an interface circuit 22 to cause it to pass information to a loop controller 24 indicating that two sets of relay contacts 26 and 28 should be closed the loop.