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6.6.8
RS-485 Communication Test
Before performing this test on the termination panel located inside the rear end
cap, verify that the wiring is correct (see
6.6.8.1
1) Using an oscilloscope, measure the line driver voltage on the termination
2) Using an oscilloscope, measure the remote request to send voltage on the
termination panel J8 or J10:
Page 6–34
Table 6–5 RS-485 Terminations
Serial Comm Port
Jumper
First or Intermediate Unit
Last or Only Unit
Table 6–6 RS-485 Field Wiring on NGC Termination Panel
Description
PIN
1
Power
2
Ground
3
Switched Power Out
4
Operate
5
Remote Request to Send
6
Transmit Bus (+)
7
Transmit Bus (-)
8
Receive Bus (+) (RS-422)
9
Receive Bus (-) (RS-422)
Instructions
Voltage on the following steps may be hard to see using a
digital multi-meter. If available, an oscilloscope will provide
a more accurate reading. To verify, the host software must
be continuously polling the meter.
Generally speaking, these tests performed on the
termination panel will only verify incorrect or damaged
wiring. If all previous testing passed and all wiring, jack and
terminations have been verified correct, the termination
panel may need to be replaced. But the termination panel
does not typically fail. Contact Totalflow customer service.
See Getting Help in the introduction of this manual for
instructions.
panel J8 or J10 between:
Port 1, J8–pin 7 (BUS-) and pin 6 (BUS+) or
Port 2, J10–pin 7 (BUS-) and pin 6 (BUS+).
When the unit is receiving data from the host, the voltage should vary
between +5 VDC and 0 VDC. This would indicate that the unit is receiving
data.
Port 1, J8–pin 2 (Ground) and pin 5 (RRTS)
Port 2, J10–pin 2 (Ground) and pin 5 (RRTS)
1
J9
pins 2–3
pins 1–2
Table
6–6).
J8–Port 1
Power
Ground
Switched Power Out
Operate
Remote Request to Send
Transmit Bus (+)
Transmit Bus (-)
Receive Bus (+) (RS-422)
Receive Bus (-) (RS-422)
2
J11
pins 2–3
pins 1–2
Description
J10–Port 2
2101510 Rev. AG
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