Installation Manual

89-041 Section 5 Issue 5 S5-3
Termination
Termination resistors are required at each end of the RS-422 connection. The effect of the
termination is to increase the input loading of that port, as seen by the talker. The figures quoted
assume that the line is correctly terminated, and allow for that extra loading.
Output drive capability
Each talker output has a capability of driving a minimum of 12 listeners on a terminated cable.
Input loading
Each receiver presents a load of approximately 12kohm to the line. Line termination resistors
are 120 ohms.
Isolation
The interface isolation is 1kV minimum throughout.
Interpretation of IEC 61162-1 sentences
GPS and Sensor Input Sentences
DTM Datum Reference
If local code is other than WGS84, then the external position source is ignored.
Field Comment
Local Datum Code interpret If it’s WGS84 or not
Local Datum Subdivision Code Ignored
Lat Offset (2 fields) Ignored
Long Offset (2 fields) Ignored
Altitude Offset Ignored
Reference Datum Code Ignored
GBS - GNSS Satellite Fault Detection
If this sentence is received, the RAIM flag will be set to TRUE. It must be repeated at least once every 10 seconds.
Field Comment
UTC Time of GGA or GNS Checks if this field isn’t empty
Expected Error In latitude Checks if this field isn’t empty
Expected Error in longitude ignored
Expected error in altitude Ignored
ID number of most likely failed satellite Ignored
Probability of missed detection Ignored
Estimate of bias in meters Ignored
Standard Deviation of bias estimate ignored