Auto-Zone Control Systems Auto-Zone CV & CV-EX Systems Installation & Operation (Version 01C) - Manual (Page 106)

Section 4
Auto-Zone CV & CV-EX
4-28 Start-Up and Troubleshooting
Checking the MiniLink Local Loop – CV-EX
Diagram
Meter Set To Read DC Volts
NETWORK
LOOP
G
T
R
G
T
R
+ -
+
-
+1.9 VDC
to
+2.1 VDC
R - to - G T - to - G
NETWORK
LOOP
G
T
R
G
T
R
+ -
+
-
+2.9 VDC
to
+3.1 VDC
To Other MiniLinks
Or CommLink
On The Network Loop To Other MiniLinks
Or CommLink
On The Network Loop
MiniLink MiniLink
To CV Controllers
And System Manager
On Local Loop To CV Controllers
And System Manager
On Local Loop
The indicated readings are typical of a normally operating system. Actual readings may vary
slightly due to the number of units installed and other factors. Any significant deviation
from these values generally indicates a problem.
Note: These tests assume that the MiniLink being checked is powered up.
Overview
Proper loop voltages are essential for reliable communications. It is normal to see fluctua-
tions on an operating communications loop. The average value should be close to the
acceptable range described below. Values will vary upon initial powerup for about 30-45
seconds. Voltages fluctuate as normal communications occur.
Measurements
Local Loop Acceptable Range
T - SHLD 2.9 - 3.1 Volts DC
R - SHLD 1.9 - 2.1 Volts DC
Action
Condition Action
Readings near zero volts. Check for shorted wiring.
If voltages are too high or too low
on either side. 1. One or more devices connected to this loop may
have damaged Comm Driver chips. Replace the
driver chip. See Figure 4-10 & 4-11.
2. Wiring errors. Check for multiple loops inadver-
tently “cross connected”, short circuits etc.