This is a simplified set of instructions for basic diagnostics.

The most important thing to remember about the APU is that Consists are based on axles. <br><br>No axles = no consist.

You will need to telnet or SSH into the RailNET APU remotely using the IP/Port, or by using a 25 pin null modem cable. Any parameter changes will need to be done from the supervisory/change menu(enter C for change). Enter, EP, to edit parameters and you will see the available options.

D – Directory

Displays the latest 15 train consists.
The RPT column shows whether each consist has been reported.
Below the directory screen is the index for RPT, showing what each letter means.
You should be able to match the same number of Tags and Cars.
- - If tags are missing:
    - - Run a DDS to check reader performance.
      - Run a SYS log to see if there are any signs pointing to a bad reader or bad antenna (reader failure/antenna failure).

DDF – Data Dump Full

Shows tag data, axle data, and any disqualifiers in the train consist.
Compare tag data to what the wheel sensor recorded.
LenFT (far-left column) shows the wheel sensor measurement—compare it to tag length to see how well the wheel sensor is performing.

DDS – Data Dump Summary

Can show wheel sensor status and the performance of each antenna/port on the RF unit.
Conversion Summary tells you if the wheel sensor is good (e.g., 0 axles lost, 0 tags lost).
Reader Summary shows RF unit performance.

Checking Issues Based on DDS

Example: Site with one bad antenna.

- - Recommend the customer use a Watt Meter (Bird 43, sold by Comet) to test RF unit output.
  - If RF output is good, check antenna connections.
  - If antenna failure shows up in DDS:
    - - In the supervisory menu:
        rfon,0,0 → test antenna 0
        
        rfon,0,1 → test antenna 1
      - Good reading: 1.2 watts or higher per antenna (5W element).

DDS Example – Lost Axles

- - If Conversion Summary shows lost axles:
    - - Usually means the wheel sensor needs calibration or replacement.
      - Could also mean you need to null your TDA105/TDA205 (Tiffenbaugh) or TDA204 (Frauscher).
      - For TDA204:
        In supervisory menu, type TDA204.
        
        Press Z to null → wait for screen to refresh.
        
        Press C to calibrate → choose R (reversal).
        
        After it refreshes, press Z to null again.
        
        Exit, then do a full reboot.
      - If calibration fails:
        Check wire connections end-to-end.
        
        Test each side of the wheel sensor with metal and check voltages in the TDA204 interface.
        
        See doc 4800012 for full voltage/calibration details.

SYS Log

- - Access:
  - SYS → 0 (all) → C (continuous).
  - Shows:
  - Wheel sensor
  - Antenna
  - Presence circuit
  - RF reader
  - Reporting / FTP/SFTP

Example: “Presence” stuck OFF:'

- - Run DDW (Data Dump Wheel) to confirm.
  - On Z3 Plus: shunt track with 0.6Ω and press calibration button.
  - On other equipment: check product manual or call Comet Support.

Reporting Issues

Run SYS log as above.
“Fatal Error on Maint 1” usually means:
- - Bad .ACC or .BAT file, or
  - Parameter change needed.

Pin 6 – Intermittent Reader Issues

Pin 6 on the PSU measures converter brick output.

3.4V or lower = replace converter bricks (Comet can repair)

VTP Issues

If DDT shows all 9’s in the left column → VTP problem.

SYS log will show Tag Time Sync Error.
Usually caused by the reader or MPAS card.
On E4 Smartpass: call Comet Support.

Upgrading AR2200 → MPRX

Check for required files:

DIR MPRX*.*
If missing, contact Comet Support.

Time

External battery on LX-800 daughter board keeps system time.
If time doesn’t hold, battery may need replacement.
To set time:
- - Supervisory menu → T
  - Enter date/time (military format).
  - shell commit
  - Reboot and verify.

Wheel Sensor Parameter Settings

Change Wheel Detector Separation, Gain, and Threshold.
Frauscher: 50 / 50 / 50
Tiffenbaugh: 40 / 99 / 30
Wrong values = lost axles.