Rockwell Automation 2708-DH5B2L_DH5B4L Attended Workstation - Manual (Page 59)

Chapter 5
Configuration Menus
5–18
A–Aux Comm Loopback Test
When Enter is pressed while A–AUX Loop Test is showing on the display,
the following prompt appears on the display:
DTR: ON CD: ON
DTR cannot be toggled OFF.
The Aux Comm Loopback Test is used to verify proper operation of the
communications line. The same pattern used by the transmit test is sent, and
the test expects to receive this pattern from the comm line. In order to use
this test, a LOOPBACK PLUG must be made or acquired.
To make an RS-232 loopback plug, use a 9-pin female D connector:
Jumper pin 2 to 3 (TxD to RxD)
To make an RS-422 loopback plug, use a 9-pin female D connector:
Jumper pin 3 to 2 (TxD + to RxD +) through a 1K ohm resistor
Jumper pin 1 to 4 (RxD– to TxD–) through a 1K ohm resistor
The 1,000 ohm resistor is placed in-line between each Receive and Transmit
pin to simulate a 1,000 ft. length of cable.
Install the loopback connector into the communications port of the
workstation BEFORE starting this test.
Once this test is started, the upper line of the display should show the
transmit pattern flashing past. If a character is lost, then the display will
freeze. This indicates a test failure. If a character is substituted, a beep will
sound and the display will pause for 3 seconds. Losing characters is
indicative of a hardware error occurring in the workstation.
The keys 1 through 9, <ENTER>, <CLEAR>, <RIGHT ARROW>, <IN>
and <OUT> will be transmitted to the comm line.
Pressing <EXIT> will terminate the test and display A–Aux Comm
Loopback Test.
Menu 6: Diagnostics
Menu Parameters (cont’d)