KEPCO TMA 4882-27 - Manual (Page 33)

TMA 4882-27 021910
3-7
Control characters, either CR or LF, are returned as XOFF CR if echo mode is on, and as XOFF
if echo mode is off. XOFF stops data from the command originator and the TMA 4882-27
returns the normal sequence of CR LF (if echo mode is enabled).
3.5.3.4 SPECIAL COMMANDS
The serial parser supports the command RSMODE to allow quick changes to RS 232 protocol.
RSMODEn This command is used to implement the XON XOFF method and control whether
echo mode is on or off. The RSMODE sequence is followed by a number n: 0,
through 5, defined in Table 3-4. This command must be the first command on a
line.
3.5.4 PROGRAMMING TECHNIQUES TO OPTIMIZE POWER SUPPLY PERFORMANCE
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.
TABLE 3-4. XON XOFF CONTROL
VALUE OF n ECHO PROMPT XON XOFF
0 OFF OFF DISABLED
1 ON ON DISABLED
2 OFF ON DISABLED
3 OFF OFF ENABLED
4 ON ON ENABLED
5 OFF ON ENABLED