SSI Link Analyser
More information
User instructions- PADs nos.:
- 086/047183 Laptop PC
- 086/047184 Master Module
- 086/047185 Optical Fibre
- 086/047186 Test Point Adaptor
- 086/047187 Trigger Module
- 086/047188 Peripheral Power Lead
Park Signalling's SSI Link Analyser (SLA) is a PC-based test tool providing a means to observe and record all messages being transferred on an SSI Trackside Data Link, in real-time. The SLA also detects and counts line glitches and corrupt or absent telegrams.
SSI Link Analyser
When the SLA is started it will 'learn' which command and reply telegrams are being transmitted on the Data Link; this information is necessary for detection of missing telegrams. A count of TFMs present on the Data Link is displayed at the bottom of the screen.
The SLA displays data and status bits for all telegrams. If a change of data or status occurs, the new data and status will be momentarily highlighted. With the addition of the SLA Trigger Module, a fully isolated programmable trigger event can be output to ancillary test equipment.
Error Detection
The SLA detects Manchester coding errors, parity bit errors, missing telegrams and glitches. If a coding or parity error is detected, the data contained in the telegram is deemed invalid and is discarded; this will also cause a missing telegram to be logged (in addition to the coding or parity error).
If a telegram is missing (or its sync or timing bits have been corrupted), it will be reported and logged as missing; the data and status display will be cleared until a valid telegram is received again.
If glitches (signal transitions which are not part of a telegram) are seen on the Data Link, the glitch count will be updated, and a log entry made.
Error counts, glitch counts and a total missing telegram count are displayed at the top of the screen, while individual missing telegram counts can be displayed for each telegram address.
SSI Link Analyser screen showing Data Link traffic
Logging
The SLA can log time-stamped events to a text file. There are three main types of events which can be selected for logging:
- Telegram changes - when the data or status bits of a telegram change, or a telegram is seen when it was previously missing.
- Errors - when a Manchester coding error, parity bit error, or glitch occurs.
- Missing telegrams - when a telegram is missing.
Connections
The laptop PC can be powered by its internal battery or from a domestic mains supply. No other power supply is required.
The SLA connects to the Data Link via a test point adaptor, terminated with banana plugs (for connection to standard SSI Data Link test points). This adaptor connects to the SLA with a fibre optic lead, thus providing complete isolation from the signalling system.