Tod Frame Field Descriptions For 1Pps +Tod Input - Symmetricom TimeProvider 5000 User Manual

Appendix B Specifications and Factory Defaults
Specifications
Table B-7. TOD Frame Field Descriptions for 1PPS +TOD Input
Field Name
Sync Char 1
Sync Char 2
Class
ID
Length
Payload
Frame Check
Sequence
(FCS)
386 TimeProvider 5000 User's Guide
Field Length
1 byte Part of Frame Header
0x43 = ASCII character "C"
1 byte Part of Frame Header
0x4D = ASCII character "M"
1 byte Basic classification of TOD message
1 byte Serial number of of TOD message
2 bytes Length of payload only
(Does not include Frame Header, Message Header,
Length Field itself, or FCS)
16 bytes Contains the message content
Two TOD messages have been defined:
Time Information Message

(see
Time Status Message

(see
Table B-10
See
definitions
1 byte Generating polynomial FCS is:
Initial value of FCS is set to 0xFF, and there is
no need to negate the input data. Checksum
calculation uses right-shift calculation, and
there is no need to negate the output frame
check data. When the frame check sequence
is transmitted, the LSB (bit 0) is transmitted
first.
Description
Table B-8
for payload contents)
Table B-9
for payload contents)
for TOD message data type
8 5 4
G(x) = x + x + x
098-00028-003 Revision A – June, 2011
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