Auto-Zone Control Systems Auto-Zone Plus Systems Installation & Operation (Version 03A) - Manual (Page 160)

Section 4 Auto-Zone Plus
4-10 Start-Up and Troubleshooting
1.3 Troubleshooting
1.3.1 Checking the CommLink IV Network Loop
Diagram
MODEM
RS-232
Serial #
COMPUTER
USB
10/100
ETHERNET
DIAG
24
V
T G R GN
D
485 LOOP POWER ACT LNK USB
Co
n fi g
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
fluctuations at this point on the CommLink IV. The average value should within the
acceptable range described below. Values will vary upon initial powerup for about 10-15
seconds 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 problem exists,
disconnect each Zone Manager
Network Loop until the problem is
isolated.
2. Replace the Commlink IV. The driver
chip is not field replaceable.