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5-10 Acutime 2000 Synchronization Kit User Guide

System Operation

5.3 Serial Data Communication

When the Acutime 2000 has acquired a set of satellites that conforms

to the mask and mode settings and has collected a valid ephemeris for

each satellite, it automatically commences periodic outputs of GPS

data and generates a timing pulse (PPS).

5.3.1 Port B

The Acutime 2000 outputs periodic TSIP health, mode, and time

messages on Port B. These status messages confirm that the receiver

is working. These packets are described in Appendix A, Trimble

Standard Interface Protocol.

The factory default port setting is 9600 baud in/out, 8 data bits, odd

parity, 1 stop bit. The serial port setting can be changed and stored in

serial EEPROM using a TSIP command.

This port can also be configured to transmit timing packets, using

packet 8E-A5 to determine which timing packet to output on this port.

5.3.2 Port A (Timing)

The Acutime 2000 has a dedicated serial port for outputting

comprehensive time packets. Messages are output after the PPS and

after external events. The factory default setting is TSIP, 9600,

8-odd-1, output only.

The host system receives both the PPS and the time packet

identifying each pulse. Use packet 8E-A5 to determine which timing

superpacket to output on this port.

The Acutime 2000 generates a packet in response to the external

event input. The event count field in packet 8F-0B (or 8F-AD)

increments for each event received. This field resets after a power

cycle and rolls over at 65535. The event tag messages are interleaved

with the PPS messages. PPS tags are distinguished by a zero (0) in the

event count field. The Acutime 2000 accepts external events up to a

1 2 ... 53 54 55 56 57 58 59 60 61 62 63 ... 319 320

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Trimble Outdoors 45005-00-ENG Manuel d'utilisateur Page 58