Consist Reporting-Confidence Logic
There are a few factors that can affect applying tags to a car. (assuming we even read tags). When we read both tags, they will be applied. Where we have to be careful is when we only read one tag. How we handle accurate reporting is called “Confidence Logic”. It is dynamically based on site conditions and parameter settings. There are 3 confidence levels and 3 “conditions” that impact tag reporting.
The key philosophy in how confidence logic works is “if in doubt, throw it out.”
You need to understand Intertrack Communications (ITC) before getting into confidence logic. When you have adjacent tracks and trains moving on both, you WILL read tags from the train on the other track. We do not want to report the wrong tag on our train, so how do we deal with it? This requires ITC is correctly cabled and configured. ITC shares data between double track APUs when both tracks are occupied to determine where to apply tags read on both APUs. Maintaining communication with the other APU is vital. Even when no data is to be exchanged, the ITC sends a "heartbeat" that is monitored on the other end. It is constantly checking for the heartbeat. If it does not receive the heartbeat, it assumes the link is down and reports ITC Fail which affects how we report singly tagged cars. The Pentium class APU with 5.x software interchanges more data than the DOS based 4.x APU and sends a different heartbeat. However, they can still be connected if properly configured. The 5.x APU will see it is receiving the 4.x heartbeat and will adjust its ITC logic to match.
The following table is from the CNF help screen on the APU. The CNF command is no longer used to setup, but its help is still there and is useful to understand CNF. The confidence settings are done in the parameter editor under AEI reporting options for each active session. These values in this example are the defaults and may need adjustment for your specific site conditions.
AEI CONFIDENCE LOGIC PARAMETERS
The following parameters are used to filter AEI data from outgoing consists based on software comparisons between AEI tag information and axle generated car information.
| Current Settings | |
|---|---|
| Default Confidence Level : 3 | |
| Double Track Active Confidence Level : 2 | |
| ITC Failure Confidence Level : 1 | |
| Conditional Options | Confidence Level Options |
| D - Default. Used when no abnormal conditions exist. | 0 - Tags are not reported. |
| T - Double Track Active. Used when train is active on adjacent track. | 1 - Tag is reported only if both left and right tags were read. |
| F - Intertrack Communications Failure. Used when APU cannot access data on adjacent track's APU. | 2 - Single tags are reported only if no discrepancies exist between car and tag information. |
| 3 - All tags are reported. | |
Confidence Level 3, report all tags:
On single track systems we typically apply all tags read, unless multiples were read over the axle platform and we don’t have a matching pair. On double tracks with single moves and ITC functioning properly, it works like a single track system. Considered condition "Default".
Confidence Level 2, report clean singles:
A single tag read on a car must fit the car. It's compared for correct axle count, car length, EGC, position where read, etc. It can still match with minor disqualifier errors, but too many and it gets reported as an untagged car. Typically, this level is used with both tracks occupied on double track sites. (and ITC functioning properly)-this condition is called:
“DTA," (Double Track Active). Also used for some single tracks where there are "presence aware" adjacent tracks where stray tags might get read.
Confidence Level 1, Must have Both tags to report:
We have to read both tags to report on the car. Typical for double track sites where the ITC communication has failed. When ITC is down, we are not sharing data with the other track's APU. We have no crosschecks or tag filtering so we have to be as defensive as possible in this state.
"ITC Fail"
Version 5.0 exchanges axle and tag data. After the train clears, the APU processes its own train and the train from data received from the other track. If a tag shows up on both consists, it is thrown out.