Auto-Zone Control Systems Auto-Zone CV & CV-EX Systems Installation & Operation (Version 01C) - Manual (Page 101)

Auto-Zone CV & CV-EX
Section 4
Start-Up and Troubleshooting 4-23
Checking CommLink Network Loop – CV-EX
Diagram
MODEM
RS-232
Serial #
COMPUTER
USB
10/100
ETHERNET
DIAG
24V T G R GN
D
485 LOOP POWER ACT LNK USB
C onf
ig
No
rm
al
To
Zone Manager
Network Loop
The CommLink IV Must Be
Powered Up For These Tests
Set Your Meter
To Read DC Volts
+ -
+ -
+
-
+
-
To 24 VAC
Power Supply
T-To-G
+2.0 VDC
To
+4.0 VDC
R-To-G
+2.0 VDC
To
+4.0 VDC
CommLink IV
Overview
This test checks for proper Network Loop voltages at the CommLink IV.
Tip: The Loop LED (located on the front panel) should “flicker” when the CommLink IV
is attempting to communicate. The Loop LED will flicker more noticeably for a few
seconds when first powered up. If the Loop LED does not flicker, the unit is defective.
Proper loop voltages are essential for reliable communications. It is normal to see fluctua-
tions at this point on the CommLink IV. The average value should be close to the accept-
able range described below. Values will vary upon initial powerup for about 10-15 sec-
onds as the unit attempts to communicate.
Measurements
Network Loop Acceptable Range
T - G (SHLD) 2.0 - 4.0 Volts DC
R - G (SHLD) 2.0 - 4.0 Volts DC
Action
Condition Action
If voltages are too high or too low
on either side. 1. Unplug the Network Loop from the CommLink
IV and check for proper loop voltages. If a prob-
lem exists, disconnect each MiniLink Network
Loop until the problem is isolated.
2. Check the CommLink IV Driver chip. Replace
the CommLink IV. The driver chip is not field-
replaceable.