SCS PTC-IIex, Manual

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10 Hostmode
10.6 Status output in hostmode
The usual status byte can be called in the hostmode by polling channel no. 254. A G poll
of this channel always outputs a string containing the actual status information of the
PTC-IIex. The format is: 254,07,0,S. (S = binary status byte). It is hence a
byte-count
format :
channel number, code, length minus one, information byte(s).
The code of the status information is 07. According to the WA8DED standard, this would
also relate to information from a connection , which, however, is usually used as a byte
count format on channel 254.
In future releases, the status information is planned to be expanded to several bytes. Using
the length information from the
WA8DED standard, a longer status information will not
lead to any problems of compatibility. The terminal program can utilize exactly that
number of bytes that are interpretable by the respective software. Newer expansions can
easily be ignored that way.
The G poll command on virtual hostmode channel 254 (“status channel”) can be extended
by a single parameter in ASCII format, valid range 0-3, e.g. G1. The parmeter determines,
how many status bytes are sent back to the PTC as a response to the G poll. The number
of bytes calculates as paramater value plus 1. Thus the command G0 is compatible with
the usual G poll without argument because it yields exactly ONE status byte, the old,
“normal” status byte. Therefore, a maximum of 4 status bytes can be requested by the
application software.
The contents of the status bytes is as following:
Byte 1: „normal“ (old/usual) status
Byte 2: PACTOR connect level:
0: not connected,
1: PACTOR-I,
2: PACTOR-II,
3: PACTOR-III.
Byte 3: “Speedlevel“ (submode of a PACTOR level):
0-1 on PACTOR-I,
0-3 on PACTOR-II,
0-5 on PACTOR-III.
Byte 4: Signed, actual receive frequency offset. Value 128 (= -128 ) is invalid and
thus should be ignored by the application software. This helps to avoid
“glitches” because the frequency byte only gets valid after the frequency
detector has obtained a stable estimate of the frequency offset.
„Auto status“ is triggered by a change of the contents of byte 1 or byte 3.
10.6.1 Auto status in Hostmode
If the status-format is set to 2 (please refer to the
STatus
command chapter 6.91 ), the
PTC provides an automatic status also in the hostmode. This mode leads to an inclusion
of channel 254 if a G poll is performed to channel 255 in the
extended hostmode , and any
change of the status has occurred in the meantime. The output could thus be:
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