- WattMaster Water Source Heat Pump Operations Manual

WattMaster WHP Section 4

4-24 Start-Up and Troubleshooting

5.3 Checking Comm. Loop Voltages

5.3.1 Checking the CommLink II Network Loop

Diagram

Overvie

This test checks for proper Network loop voltages at the CommLink II.

The Loop LED (located on the front panel) should “flicker” when the CommLink II 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.

Make sure CommLink II jumper is set to “Multi” position.

Proper loop voltages are essential for reliable communications. It is normal to see fluctua-

tions at this point on the CommLink II. The average value should be close to the acceptable

range described below. Values will vary upon initial powerup for about 10-15 seconds as

the unit attempts to communicate.

Measurements

T - G (SHLD) 2.9 - 3.1 Volts DC

R - G (SHLD) 1.9 - 2.1 Volts DC

Action

If voltages are too high or too low on either

side

1. Unplug the Network loop from the

CommLink II and check for proper loop

voltages. If a problem exists, disconnect

each MiniLink Network loop until the

problem is isolated.

2. Check the CommLink II Driver chip.

Replace the driver chip if necessary