Difference between revisions of "TD"
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BarryCarlyon (talk | contribs) (Added sample messages) |
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== Overview == | == Overview == | ||
| − | + | === What on earth is this? === | |
| − | + | The TD feed provides low-level detail about the position of trains and their train reporting number through a network of berths. Usually, but not always, a berth is associated with a signal - but there are locations (such as terminal platforms at stations) where there may be more than one berth. | |
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| − | + | From each berth, there are zero or more other berths which a train description may move, or 'step' in to. Some of these may be one-way, some may be two-way. | |
| − | == | + | === Message types === |
| − | + | The Train Describer feed has four message types: | |
| − | + | * CA - Berth Step, where a description moves 'from' a berth, 'to' another berth | |
| − | + | * CB - Berth Cancel, where a description is removed from a berth | |
| − | + | * CC - Berth Interpose, where a description is interposed (placed in to) a berth | |
| − | + | * CT - Heartbeat | |
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| − | + | With the exception of the CT message type, TD messages include a four-character train description. At present, only class 1, 2 and 9 trains are included in the feed. | |
| − | + | == Format == | |
| − | + | Messages are sent in JSON format, as follows: | |
| − | + | * {"CA_MSG"=>{"time"=>"1349696911000", "area_id"=>"SK", "msg_type"=>"CA", "from"=>"3647", "to"=>"3649", "descr"=>"1F42"}} | |
| − | + | * {"CB_MSG"=>{"time"=>"1349696911000", "area_id"=>"G1", "msg_type"=>"CB", "from"=>"G669", "descr"=>"2J01"}} | |
| − | + | * {"CC_MSG"=>{"time"=>"1349696911000", "area_id"=>"G1", "msg_type"=>"CC", "descr"=>"2J01", "to"=>"G669"}} | |
| − | + | * {"CT_MSG"=>{"time"=>"1349696911000", "area_id"=>"SA", "msg_type"=>"CT", "report_time"=>"1249"}} | |
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Revision as of 11:54, 8 October 2012
Overview
What on earth is this?
The TD feed provides low-level detail about the position of trains and their train reporting number through a network of berths. Usually, but not always, a berth is associated with a signal - but there are locations (such as terminal platforms at stations) where there may be more than one berth.
From each berth, there are zero or more other berths which a train description may move, or 'step' in to. Some of these may be one-way, some may be two-way.
Message types
The Train Describer feed has four message types:
- CA - Berth Step, where a description moves 'from' a berth, 'to' another berth
- CB - Berth Cancel, where a description is removed from a berth
- CC - Berth Interpose, where a description is interposed (placed in to) a berth
- CT - Heartbeat
With the exception of the CT message type, TD messages include a four-character train description. At present, only class 1, 2 and 9 trains are included in the feed.
Format
Messages are sent in JSON format, as follows:
- {"CA_MSG"=>{"time"=>"1349696911000", "area_id"=>"SK", "msg_type"=>"CA", "from"=>"3647", "to"=>"3649", "descr"=>"1F42"}}
- {"CB_MSG"=>{"time"=>"1349696911000", "area_id"=>"G1", "msg_type"=>"CB", "from"=>"G669", "descr"=>"2J01"}}
- {"CC_MSG"=>{"time"=>"1349696911000", "area_id"=>"G1", "msg_type"=>"CC", "descr"=>"2J01", "to"=>"G669"}}
- {"CT_MSG"=>{"time"=>"1349696911000", "area_id"=>"SA", "msg_type"=>"CT", "report_time"=>"1249"}}
