Heat Controller Water Source Heat Pump - Manual (Page 114)

WattMaster WHP Section 4
4-32 Start-Up and Troubleshooting
5.3.8 Checking the MiniLink Local Loop Driver
Diagram
Meter Set To Read DC Volts
The indicated values are typical of a normal operating system. Actual readings may deviate
slightly.
Note: These tests assume that the MiniLink is powered up.
Overview
This test checks for proper Local Loop voltages coming from the MiniLink.
Tip: The Local Loop LED (located near the connector) should “flicker” when the Mini-
Link is operating and when first powered up. If the LED is not flickering, the unit is
not functioning.
Proper loop voltages are essential for reliable communications. It is normal to see fluctua-
tions at this point on the MiniLink. The average value should be close to the acceptable
range described below. Values will vary upon initial powerup for about 10-15 seconds. The
voltage will fluctuate as the unit attempts to communicate.
Measurements
Local Loop Acceptable Range
T – G
(SHLD) 2.9 - 3.1 Volts DC
R – G
(SHLD) 1.9 - 2.1 Volts DC
Action
Condition Action
If voltages are too high or too low on either
side 1. The MiniLink has a damaged Comm
Driver chip. Locate and replace the
driver chip(s). See "1.3.11 Comm
Driver Chip Replacement”.
2. The MiniLink is not functioning.