Ensure the Panel and Popex board area in working condition:
1. Remove all other wires from the D8125 data loop terminals and connect a single known good D9127 popit to the D8125. 2 . Use View Point Status to see if the D9127 reports Normal/Open/Short or is missing. a. If a known good popit reports missing in View Point Status, replace the D8125 with a known good board and repeat the test. b. If a known good D9127 popit and known good D8125 still shows missing, then the panel should be replaced. Note: Failed D8125 boards are uncommon and an unlikely cause for all Popit points going missing. Ensure a good popit is used for testing.
Test field wiring
1. Remove all of the popit loop wires from the data loop terminals of the D8125 board. 2. Locate a good earth ground to use as a reference.
NOTE: Ensure the best possible earth ground is used for testing.
3. Measure for Resistance to Earth Ground between each of the removed popit loop wires and the earth ground reference. - The meter should read open. Any measurement of resistance to earth ground, whether very high or low, indicates a short to earth ground which can cause all popit points to go missing. Troubleshoot by 'half-splitting' the loop wiring to isolate the resistance measured to earth ground. 4. Measure for AC voltage to Earth Ground between each of the removed popit loop wires and the earth ground reference. - The meter should read either 0VAC or very low AC voltage less than 1VAC. If the reading is nearly 1volt AC or more than 1VAC there is AC induction on the popit loop which can cause all of the points to go missing. Troubleshoot by 'half-splitting' the loop wiring to isolate the AC measured to earth ground.
Shielded cable is not recommended, if used ensure properly grounded Common causes of AC induction are: 1. Ungrounded drain wire 2. Multiple ground points of the drain wire 3. Disconnected drain wire between devices somewhere in the loop.
Ensure proper polarity in the popit loop. 1. Reversed polarity in the popit loop may cause the two ceramic resistors on the D8125 to become dangerously hot. Carefully check the ceramic resistors for high temperature. 2. If the single popit does not display missing in view point status and previous steps do not detect a problem, 'half-split' the popit loop while checking View Point Status for working points to isolate . a. Connect one popit loop to the D8125, go half way out into the loop and disconnect the remaining Popits. b. Using View Point Status, determine if the Popits still connected in the loop show missing or normal/open/short.
Figure 1 D8125 Ceramic Resistors
Inspect for excessive data distance T-Taps are not recommended. Because data distance is additive the total distance must be added corectly. Add the distance from the D8125 to the junction point plus the distance to the end of each connected tap.
a. Maximum Length of All Data Expansion Loops Combined AWG (mm) Length Ft. (m) 22 (0.8) 1,800 (549) 20 (1.0) 2,890 (881) 18 (1.2) 4,600 (1,402) 16 (1.5) 7,320 (2,231) 14 (1.8) 11,650 (3,551)