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Message Trapper II

The S&C Model 20301 Message Trapper II (MT) is a small, portable tool    intended for use by signal maintainers to verify that signal equipment status at a location is accurately reflected in the communication sent into the PTC system.  It is designed to sit astride the message flow and monitor and record messages sent from the Wayside Interface Unit (WIU) to the Wayside Message Server (WMS) or, alternatively, messages sent from the WMS to the PTC Radio.   The message recording feature is  commonly applied as a trouble-shooting tool for clear-on-arrival situations.

Signal location equipment status messages are displayed graphically, in real time, resulting in the status being easily recognized as seen in the following representation.

Information boxes are colored to match aspect colors and switch positions are represented with a large, bold “N“, “R” and “T” (in transition).  With the WIU to WMS and WMS to Radio messages reduced largely to graphic symbols, the skill level required to make effective use of the MT II is also reduced.  Further, graphics over text, shortens the time it takes for the brain to absorb the information in the message flow.  This speed of recognition makes detection of glitches in the flow more likely.  MT II is helpful in resolving status conflicts between the signal and PTC systems.  The recording feature has proven to be especially helpful in a maintenance, trouble-shooting application at locations where intermittent, clear-on-arrival problems occur.

The MT is connected in bridging mode, with the two devices in the link selected for observation. Connection is made using the “Network” “A” or “B” jacks on the MT.  The MT is furnished with two 5 ft CAT 5 cables.   In copying and recording these messages, the MT will not cause any modification to the messages themselves.  Appropriate PTC libraries and local territory XML files are preloaded into the MT. The maintainer, by location, will select the pertinent files to enable his monitoring of the message flow. He will see a live stream of from the WIU or, alternatively, WMS.  These message copies will use the Timestamp and address from the message, maintaining its unmodified state and identifiability. All messages received between changes in state will be screened out and discarded.  Additionally, if no messages are received for any period of time longer than 15 seconds, the Message Trapper will “Alarm”, to alert the user that no transmission has been detected.  This alarm will be logged and will remain present until the user clears it, or until the message stream returns.

Each copied message will be recorded to a log. This log will be saved to an SD card or USB Memory Stick and will be accessible from the Message Trapper display as well as by transferring stored data into a PC spreadsheet.  Spreadsheet headers for the message segments will be provided in the MT firmware. Capacity of the storage of messages and alarms is limited only by the size of the SD Card or USB.

Memory Stick used.  An 8GB SD Card is provided.  Each railroad has assigned its own signal aspect, relay status, switch position, etc., terminology to the bits transmitted by the WIU. This information and the location-specific XML files are transferred to the MT by the railroad.   This enables the MT to be a generic product, customized by the railroad, transit system or contractor purchasing it. Operating temperature range:  32 deg F to +140 deg F (0 deg C to +60 deg C).  Storage temperature range:  -22 deg F to +176 deg F (-30 deg C t0 + 80 deg C) Fatal injury will occur to the display if the storage temperature range is exceeded in either direction.  No power switch.  Input Power:  120VAC to 12VDC by Adapter, PN:  330-11A (furnished) or case or house battery @ 12VDC, with Cord PN:  1010-30-18 (furnished).  Current usage:  2.5A Max at 12V.  Physical Size: 9.8 in. x 9.8 in. x 4.0 in. Comes complete with two 5 ft CAT 5 Cords, 8GB SD Card, web carry strap and HD, zippered carry bag.


Message Trapper, complete with two 5 ft, CAT 5 Cords; 5 ft. power cord for connecting the Message Trapper to 12VDC case or house battery; 330-11 Universal Power Supply; web carry strap and HD, zippered carry bag20301A-1000
Above, but with accessory Mini, ASCII keyboard20301A-1001
Top, but with accessory Micro, ASCII keyboard20301A-1002
5 ft. CAT 5 Cord03-2047
5 ft. Power Cord for Connecting MT to case or house battery1010-30-18
SD Card, 8GB1010-15
Web Carry Strap w/attachment clips, 14 in.02-7091-10
120VAC to 12VDC, 4.4A Power Adapter330-11A
Message Trapper, only20305A
Keyboard, Mini, ASCII, USB connection331-5-19
Keyboard, Micro ASCII, wireless331-5-20