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Chapter 8
Troubleshooting and Maintenance
TXEN Test
8–12
Only available on the RS-485 version. Use the TXEN test to verify the
transmit enable line at the RS-485 communications port.
The TXEN test requires a loopback connector with an LED. You can
construct a simple loopback connector as shown below:
RS-485 Port Only
DB9 Female
Pin Signal Name
1
Data Out –
2
Data Out +
3
Data In -
4
Data In +
5
Signal Ground
6
Transmit Enable
7
Not Used
8
Signal Ground
9
Shield
To test the transmit enable line:
1. Use the [NEXT] and [PREV] keys to display TXEN Test on the
test selection screen.
DTAM Micro Diag Test
2. Press [
] to initiate the test.
The LED should flash at approximately 1 second intervals indicating that
the transmit enable line is functioning properly.
3. Pressing [
] terminates the TXEN test.
The next test selection screen is displayed.
DTAM Micro Diag Test
4. To terminate the test function , press the [NEXT] and [PREV] keys to
display Reset DUT in the test selection area. Press [
terminal.
LED
750W
TXEN Test
Reset DUT
Loopback Connector
Connects pins 1 !3
and pins 2 ! 4
LED and 750W resistor
between pins 2-4 and 6
] to reset the
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