BOP HIPWR 111315 3-43• –V_LIM_EXT (pin 6) - This +1V to +10V analog signal sets the negative voltage protectlimit from 10% of the nominal value to –full scale voltage. +10V corresponds to ratedminimum (maximum negative) voltage (e.g., for BOP 36-28MG, +10V sets negative volt-age limit to –36V).• +I_LIM_EXT (pin 13) - This +1V to +10V analog signal sets the positive current protectlimit from 10% of the nominal value to full scale current. +10V corresponds to rated max-imum current (e.g., for BOP 36-28MG, +10V sets positive current limit to +28A).• +V_LIM_EXT (pin 14) - This +1V to +10V analog signal sets the positive voltage protectlimit from 10% of the nominal value to full scale voltage. +10V corresponds to rated max-imum voltage (e.g., for BOP 36-28MG, +10V sets positive voltage limit to +36V).The maximum frequency of an a-c signal used for the external protection limit must be at least100 times lower that the sampling rate of the external signal (100Hz), resulting in a bandwidth of1Hz.The external programming circuit must be able to sink 0.15mA maximum provided by the BOP.When the input is an open circuit, the corresponding input signal automatically goes to 20%above the nominal protection limit.NOTE: Each time Protection Limit setting is changed, the unit generates an internal *RSTreset command (see PAR. A.11) requiring the BOP output to be reprogrammed.3.4.4.1 USING BOTH LOCAL/DIGITAL AND EXTERNAL PROTECTION LIMITSWhen PROTECTION LIMIT on the Reference Menu is set to Lesser Limit, the protect limits areautomatically selected from either 1) the external analog voltage applied to the Analog I/O port(see PAR. 3.4.4) or 2) the value set from the keypad or SCPI command. Whichever limit has alower absolute value (closest to zero) has effect.To be functional this feature must first be configured from the front panel. From the power-upscreen press $, and highlight Protection Limit. Press ! to modify, then highlight Lesser Limitand press $ to save. Then press % to apply the changes (without saving for power-up) andexit. NOTE: Each time Protection Limit setting is changed, the unit generates an internal *RSTreset command (see PAR. A.11) requiring the BOP output to be reprogrammed.3.4.5 MONITORING OUTPUT CURRENT USING AN ANALOG SIGNALThe BOP provides an output analog signal, 0 to ±10V, that is proportional to the output currentwhich is always available. For the master of a parallel or series configuration this signal is pro-portional to the output current of the parallel or series combination. This signal is available at pin3, referenced to pin 10, of the Analog I/O port. To protect the BOP circuitry this signal is providedvia a series 2K ohm resistor, thus requiring a high impedance monitoring device or instrument.3.5 DIGITAL REMOTE MODE PROGRAMMINGBOP models may be digitally programmed over a control bus using SCPI (Standard Commandsfor Programmable Instruments). SCPI provides a common language conforming to IEEE 488.2for instruments used in an automatic test system (see PAR. 3.6). The control bus used must beeither the IEEE 488 standard communication bus (General Purpose Interface Bus, GPIB), or theRS 232C Serial Bus.
