Data I/O 298 Manual page 92

Controller
If it has been determined from preliminary troubleshooting
that a problem exists in the controller, do the following:
1. Check that all socketed devices are seated firmly and all
soldered components are intact. Check that jumpers JP1
through JP5 are installed.
2.
With an oscilloscope, detemine if the V•02 timing signal
is present by observing pin 7 of U5 on the controller
board. if it is not present, check that the programming
module is grounding pin
HH
(TP3) on J7 (the
programming module interface).
3. If steps 1 and 2 do not reveal the problem, contact your
Data 1/0 Service Center.
Serial Interface Circuitry
If it has been determined from preliminary troubleshooting
that a problem exists in the serial interface, do the
following:
1 . Use an oscilloscope to observe the signal on pin 3 of
U14 on the controtter card. The frequency of the signal
at pin 3 should be 16 times the selected baud rate.
(Baud rate
=
[1 /time] divided by 16.)
2. Perform steps a through d. A failure in any step
indicates a failure in the ACIA (U14) or the drivers U9 or
U10).
a. Initiate a copy from the data RAM to the
serial port.
b. Check the voltages at U14, pins 23 and 24. Both
should read 0.0 to 0.5 V.
c. Press START.
d. Use the oscilloscope to observe pin 2 of the serial
interface. The 29B should be transmitting data at the
selected baud rate. Perform the following procedure
(see figure 4-6).
(1) Turn 29B power on.
(2) Set baud rate to 9600.
(3) Using select function A2, enter 00 hex data into
all of RAM.
(4) Connect oscilloscope probe to pin 2 of serial port
connector J3.
(5) Copy RAM to port using 0 (default) values for
beginning addresses and maximum (default) block
size.
(6) Observe the waveform. It should be similar to
figure 4-6(b).
(7) Using select function A2, enter FF hex data.
(8) Repeat steps (4) and (5) above.
(9) Observe waveform. It should be similar to
figure 4-6(a).
Q
z
::>
0
a:
c:1
.±
4-9
10-990-0013
298 TRANSMIT FROM SERIAL PORT
a)
OUTPUT OF "FF" DATA
29-8 TRANSMIT FROM SE-RIAL PORT
b) OUTPUT OF ZEROS "08" DATA
Figure 4-6. Checking Baud Rate on Pin 2