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PK-88 OPERATING MANUAL
6.4.1.
Symptom: PK-88 does not communicate with the terminal
Use a 'breakout box' or oscilloscope to verify that correct control voltages are present on
pins 4, 5, 6 and 8 of J1, the RS-232 I/O connector.
o
Verify that the RTS line on Pin 4 of J1 (the RS-232 1/0 connector) are not being held
low.
If the PK-88 software flow control is disabled by setting XFLOW to OFF, the controller will
not send data to the terminal unless RTS is asserted.
If the computer or terminal does not provide the DTR/CTS protocol or "handshake", the
DTR/CTS lines (pins 20 and 5 on J1) should not be connected.
o
Verify that the voltages on the PK-88 are correct.
If the tests are valid, verify the signal on U12 pin 27 with an oscilloscope.
o
Recycle the power switch on the PK-88. Transitions on this pin shortly after reset in-
dicate that the PK-88 is sending data.
o
Verify that transitions are also present on U4 pin 13.
6.4.2.
Symptom: PK-88 signs on with mutilated data
If the terminal displays strange characters, 'garbage', graphics, etc., one or more of the
following parameter values is incorrectly set and does not agree between the terminal and
the PK-88:
o
Set the terminal rate to 1200 baud if possible, seven data bits, even parity, and one
stop bit. These are the default settings stored in the PK-88's EPROM.
o
Restart the PK-88 by cycling the power switch OFF then ON (out then in). The sign
on message should appear.
If the PK-88 still prints gibberish:
o
Verify that the terminal is set to 1200 baud and recycle the power switches on both
the PK-88 and terminal.
If the sign-on message still fails to appear:
o
Verify signals with an oscilloscope connected to TXD pin 25 of U12, the Z8530A
chip, and then at the X32 baud rate clock (38.4 kHz at 1200 baud) on pin 14 of
U12.
data rate (TBAUD)
data word length (AWLEN)
parity (PARITY)
number of start and stop bits
6 - 5
TROUBLESHOOTING
PK-88 - 147
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Table of Contents
Troubleshooting
