160 XFC G4 2103335 Rev AB
Table 21: RS-485 Terminations
First or Intermediate Unit
7.4.7 RS-485 Communication Test
Tools needed:
-Oscilloscope
-Flat head tweeker screwdriver
To perform an RS-485 communication test using an oscilloscope:
IMPORTANT NOTE: Voltage on the following steps may be hard to see using a multimeter. If available, an
oscilloscope will provide a more accurate reading. To verify, the host software must be continuously polling the
meter.
Open enclosure
Measure line driver voltage, using an oscilloscope, on the circuit board J4 between:
a. COMM 1, pin 7 (BUS-) and COMM 1, pin 5 (BUS+)
b. COMM 2, pin 13 (BUS-) and COMM2, pin 12 (BUS+)
IMPORTANT NOTE: When the unit is receiving data from host, voltage should vary between -5Vdc and 0Vdc.
This would indicate that the unit is receiving data, continue to step 3. If unit is not receiving data, investigate wiring
issues (Table 19:).
Using an oscilloscope, measure remote request J4 to send (RRTS) voltage J6 between:
a. COMM 1, pin 2 (Ground) and COMM 1, pin 8 (RTS) or
b. COMM 1, pin 2 (Ground) and COMM 2, pin 14 (RTS).
IMPORTANT NOTE: When the unit is receiving data from host, voltage should vary between +5Vdc and 0Vdc.
This would indicate that the RRTS is receiving data. If unit is not receiving data, investigate wiring issues (Table
19:).
Call Totalflow Technical Support for additional help. If a communication problem still exists, and the unit has passed
the tests in steps 1 and 2, additional testing will be required.
CAUTION – Equipment Damage: Before removal or installation of either the above communication interface
modules, it is important that you disconnect the external battery charger and main battery pack cable connectors
from the circuit board.
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