KEPCO BHK-MG 200W (Full Rack) Series - Manual (Page 62)

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BHK-MG (OPR) 022014
• Choose external trigger source by sending TRIG:SOUR EXT (PAR. B.92)
• Choose continuous action (by sending INIT:CONT ON (PAR B.12).
NOTE: The output must be enabled prior to activating the external trigger at pin 4 of the External
Trigger port in order for the external trigger to work properly.
3.3.5 BHK-MG VISA INSTRUMENT DRIVER
The VISA instrument driver simplifies programming with a VISA compatible GPIB controller. and
Includes 1) source code (C) for all VISA functions, and 2) a complete programming reference
manual which can be used to program one or more BHK-MG power supplies using a virtual front
panel observed on a computer monitor.
Download the latest VISA driver from the Kepco website at
http://www.kepcopower.com/drivers.htm
Although the software drivers supplied by Kepco are VISA compliant, they also require the
installation of the proper 32-bit VISA driver from your GPIB card supplier. Many vendors supply
this software with the hardware; National Instruments (http://www.natinst.com) has the driver for
their cards available on the internet at a file transfer site (ftp://ftp.natinst.com — find the folder
for support and VISA drivers). The driver to be installed is the win16 driver, even if your system
is running under Windows 95 or Windows NT.
3.3.6 PROGRAMMING TECHNIQUES TO OPTIMIZE PERFORMANCE
3.3.6.1 PROGRAMMING VOLTAGE/CURRENT LIMIT AND CURRENT/VOLTAGE LIMIT
Kepco's auto-crossover digital supplies can operate in either voltage mode with current limit, or
current mode with voltage limit. The operating mode is determined by the voltage and current
commands received, as well as the load. Each time voltage and current commands are
received, the unit must evaluate the commands and the load conditions to determine the proper
operating mode. Reducing the number of times this evaluation must be made is desirable
because Kepco's digital auto-crossover supplies employ two separate feedback loops. Each
time there is a potential mode change, there is always an uncontrolled period of a few millisec-
onds while the two feedback loops compete for control of the output. By changing only the
active parameter (e.g., voltage for voltage mode), there is no doubt as to what the operating
mode will be, so the unit is never uncontrolled, response is quick and no transients are possible.
Recommended programming techniques are:
1. Minimize programmed mode (voltage or current) changes. Unless absolutely required by the
test parameters, allow the power supply to automatically switch modes as determined by the
load. This will improve response time and reduce undesirable transients. For those power
supplies that employ relays (Kepco's MBT with “R” option, MAT and MST) this will also
increase the life of the relay.
2. Once the mode (voltage or current) is programmed, program the active parameter to zero
and the complementary limit parameter to the maximum anticipated for application. Then
program only the active parameter. The active parameter is the parameter that controls the
output, e.g., voltage controls the output in voltage mode.