NOTE: This module has been replaced by the 1756HP-TIME module
1756HP-GPS
GPS Precision Timing
Hiprom presents the 1756HP-GPS for the Allen-Bradley ControlLogix platform. By harnessing the power of the Global Positioning System, this module is able to provide precision timing information across the ControlLogix backplane. Other GPS information is also available including Position, Velocity and GPS receiver status.
Module Configuration
The 1756HP-GPS module slots directly into any ControlLogix chassis, interfacing with, and deriving all required power from, the backplane. The on-board GPS receiver connects to an external active antenna by means of an antenna patch lead. These items are supplied with the module. In order to achieve the maximum timing accuracy the GPS module should be located in the local rack, that is, the same rack as the ControlLogix CPU. The module is pre-configured in one of three variants :
Timing
Precision time is provided across the backplane by means of a scheduled connection between the GPS module and ControlLogix CPU. The time data is formatted in Year, Month, Day, Hour, Minute, Second and Microsecond for ease of use. This time can also be configured to follow a local time zone and thus accommodate daylight saving. Universal Co-ordinate Time (UTC) is also available, reflecting the number of microseconds since January 1, 1972. When adding the 1756HP-GPS module to the ControlLogix I/O Configuration the Requested Packet Interval (RPI) can be set as low as 0.5 ms. Time will be synchronous to other GPS time sources.
Sequence of Events Recording
Five millisecond accurate Sequence of Events Recording can easily be achieved in the ControlLogix CPU by executing a simple ladder routine in a periodic task. For this purpose it is recommended that both the GPS module and the Input modules used for Sequence of Event generation be located in the local rack. Far better accuracy (<100us) can be achieved through the use of the Allen- Bradley Sequence of Event module (1756- IB16SOE) by translating the SOE Coordinate System Time (CST) to UTC and local time standards.
Position and Velocity
The 1756HP-GPS module also provides GPS position and velocity fixes. Position data is available in both polar co-ordinates of Longitude , Latitude and altitude as well as in Cartesian Earth-Centered-Earth- Fixed (ECEF) coordinates X,Y and Z. Similarly velocity is available in Northerly, Easterly and Upward velocity components as well as ECEF Vx, Vy and Vz. Change of Base Algorithms can be supplied to translate position & velocity to a local coordinate system. The internal GPS receiver provides position updates every second with a horizontal accuracy of less than 6m (50%). Higher precision options are available on the 1756HP-GPS module. For details please contact your local distributor.
Status
All module and GPS status information is available across the backplane. This includes the number of satellites locked, validity of GPS data as well as the location and signal strength of each satellite being tracked.