KEPCO BHK-MG 40W (Half Rack) Series - Manual (Page 65)

BHK-1/2-MG 121313
3-21
3.5.3.2 PROMPT METHOD
The command originator sends a message line (command) to the BHK-MG and waits until the
prompt sequence CR LF > (3E
H
, 62
10
) is received. The BHK-MG sends the prompt sequence
CR LF > to the command originator indicating the power supply is ready to receive the next
command and data will not be lost. The prompt method is similar to the echo method described
above, except that the command originator does not have to compare each character and
repeat any characters dropped while the IEEE 1118 bus (BITBUS) is active. The operation of
the BHK-MG is identical for echo mode and prompt mode; implementation of prompt mode is at
the command originator.
3.5.3.3 XON XOFF METHOD
The XON XOFF method allows the BHK-MG to control when the command originator is allowed
to send data. The command originator can only send data after the XON (transmission on) char-
acter (011
H
) has been received; the command originator stops sending data after receiving the
XOFF (transmission off) character (013
H
), and waits until the XON character is received before
sending additional data.
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 BHK-MG returns the
normal sequence of CR LF (if echo mode is enabled).
3.5.4 ISOLATING RS 232 COMMUNICATION PROBLEMS
A Loop Back test can be run from the front panel to aid in isolating RS 232 communication prob-
lems. The unit is designed to pass the test only with the Loop Back test connector (part of Kit
219-0436, see Table 1-5) installed.
1. With the power supply in local mode, command entry status , press MENU key until LCD
reads
LOOP BACK TEST UNTESTED 1=RUN
.
2. Press the 1 key to run the test with the Loop Back Test connector NOT installed and verify
the LCD reads
FAILED
. If the LCD reads
PASSED
, the power supply is defective and
requires repair.
3. Install the loop back test connector into RS 232 port and press the 1 key to rerun the test. If
the LCD reads
PASSED
, the power supply is operating properly. If the LCD reads
FAILED
,
the unit requires repair.
4. To test the integrity of the cable assembly connecting the power supply RS 232 port to the
computer, remove the Loop Back test connector from the power supply RS 232 port and
connect the cable in its place. With the DB9 adapter installed on the opposite end of the
cable, connect a short jumper wire between pins 2 and 3 of the adapter connector and
repeat the test of (3) above. If the LCD display reads
FAILED
, the cord is either the improper
type (not null modem) or is defective. If the LCD display reads
PASSED
, the cable is correct;
remove the jumper and reconnect the cable to the computer.
If each of the above steps is completed successfully, the problem lies in the computer hardware
and/or software. Refer to the Product Support area of the Kepco website for additional informa-
tion regarding RS 232 communications problems: www.kepcopower.com/support.