The packet 'F' format is as follows:
byte 1 S O H
byte 2 ' F '
byte 3 ' 2 ' for asynchronous '5' for synchronous
byte 4
' 0 '
- 'F" m l bits 12-15
byte 5 ' 0 ' - 'F' m l bits 08-11
byte 6 ' 0 ' - 'F' m l bits 04-07
byte 7 ' 0 ' - 'F' m l bits 00-03
byte 8 ' 0 ' - 'F' m 2 bits 12-15
byte 9 ' 0 ' - 'F' m 2 bits 08-11
byte 1 0 ' 0 ' - 'F' m 2 bits 04-07
byte 1 1 ' 0 ' - 'F' m 2 bits 00-03
byte 1 2 E T B
I f a '2' (asynchronous) qualifier is used then the values of nl and n2 are the same as the packet values
m and m2. I f the '5' (synchronous) qualifier is used, then the values of n1 and n2 are equal of packet
values m+1 and m2+1 respectively. For example, if a synchronous 500KHz square wave is desired
then the qualifier byte is '5', m = 9, and m2 = 1. Additional insight into the operation of the counter
can be gained by reading the INTEL documentation for the 82C54 integrated circuit. The '2' and '5'
qualifiers correspond to the INTEL defined modes 2 and 5.
4.1.6 PACKET 'G' OFFSET CONTROL
It is frequently desired to program an offset into the basic TFP timekeeping functions relative to the
reference input. For example, if the reference input is an IRIGB timecode, there may be significant
cable delay between the IRIGB generator and the TFP location. Packet 'G' allows this time
difference to be removed by inserting the known amount of offset between the IRIGB reference and
TFP locations. The offset is programmable in units of 100 nanoseconds, and may be positive or
negative. The format is shown below.
byte 1 S O H
byte 2 ' G '
byte 3 ' + ' or '' advance or retard
byte 4 ' 0 ' - '9' BCD millisecond hundreds
byte 5 ' 0 ' - '9' BCD millisecond tens
byte 6 ' 0 ' - '9' BCD millisecond units
byte 7 ' 0 ' - '9' BCD microsecond hundreds
byte 8 ' 0 ' - '9' BCD microsecond tens
byte 9 ' 0 ' - '9' BCD microsecond units
byte 1 0 ' 0 ' - '9' BCD nanosecond hundreds
byte 1 1 E T B
For the IRIGB scenario described above a positive offset should be used.
Datum Inc., Bancomm Div.
bc635VME/bc350VXI Manual
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