Installation Manual

30 Issue 1 AIS Installation Manual
7.1 Technical Information
7.1.1 RS-422 interfaces
The Transponder has eight RS-422 interfaces:
• 4 sensor data input ports SEN1, SEN2, SEN3 and SEN4
• 2 Bi-directional input/output ports MAIN and AUX/Pilot
• 1 Bi-directional input/output port RTCM
• 1 Bi-directional input/output port Long Range
All communication interfaces are compatible with IEC61162-1 (2000) and IEC61162-2 (1998)
standards.
7.1.2 Termination
Termination resistors are required at each end of the RS-422 connection, to match the
impedance of the line to minimise reflections. The figures quoted assume that the line is
correctly terminated, and allow for that extra loading.
7.1.3 Output drive capability
Each talker output has a capability of driving a minimum of 12 listeners on a terminated cable.
7.1.4 Input loading
Each receiver presents a load of approximately 12 kohm to the line. Line termination resistors
are 100 ohms.
7.1.5 Isolation
The interface isolation is 1 kV minimum throughout.
7.2 RTCM binary messages
The RTCM port on the transponder accepts incoming messages from a differential beacon
receiver in RTCM binary format and outputs messages in RTCM binary format. Differential
correction data received on the VHF data link (in message 17) is also output to the RTCM port
in RTCM binary format.
7.3 NMEA sentences used
The ports on the M-2 transponder accept and output different combinations of NMEA sentences
as follows:
Port Input sentences Output sentences
Main, Display and Aux
(“Presentation ports”)
ACA, ABM, BBM, ACK, AIR,
AIQ, LRI, LRF
ABK, ACA, ACS, ALR, LRI, lRF,
LR1, LR2, LR3, SSD, TXT, VDO,
VDM, VSD
Long Range LRI, LRF LRI, LRF, LR1, LR2, LR3
S1, S2, S3 and S4
(“Sensor ports”)
DTM, GBS, GGA, GLL, GNS,
HDT, RMC, ROT, VBW, VTG
None