SCS PTC-IIex, Manual

Page: 156 / 220

10 Hostmode
10.4.36 %V
Displays a short ASCII string containing the actual version number of the actual version
number of the PTC-IIex firmware and the actual version number of the PTC-IIex BIOS.
Characters left of the dot are the main version number of the firmware. Characters after
the first dot until the first blank are the sub-firmware version number. Letters may also
appear here. At least one blank separates the firmware version number and the BIOS
version number. The BIOS version string is built in the same way, the convention just
refers to the second dot this time.
Format for example: 2.8 1.32
10.4.37 %W
For synchronizing external scanners
Possible arguments: 0 or 1 (ASCII).
All responses to the %W command are null-terminated ASCII strings.
The %W command enables synchronizing between the PTC and external frequency
scanners. Examples for external frequency scanners are AirMail and WinLink2000. These
PC programs subsequently search for incoming user calls on some different channels,
changing the actual frequency by its own without the aid of the internal PTC scanner
(trx:-menu). Thus there exist a (small) risk that a frequency change occures when the
internal scanner would not allow/perform a frequency change or more generally speaking
when a frequency change is prohibited due to a special actual state of the modem, e.g.
when the modem has already detected the beginning of a user access on the PACTOR HF
port.
In principle this problem can already be solved by using the scan-stop signal the PTC
provides - but only if the external scanner immediately recognizes the scan-stop signal.
Unfortunately, so-called latency time (Windows) is introduced in practise. Latency time
delays the scan-stop signal and thus can cause “prohibited” frequency changes. An
example of a typical szenario: A user calls on channel A. The PTC has already detected
that it is being called and asserts the scan-stop signal - but unfortunately some time
(latency) elapses until the external scanner finally receives the scan-stop information.
Therefore, it’s not unlikely that the scanner still changes the frequency (during the latency
period) to channel B although the PTC has already indicated that the scanner should stop
operation. The result is catastrophic: The system responses on channel B although the
user called on channel A. The connection fails.
The %W command fully resolves this problem with the aid of a special mechanism,
regardless of the amount of latency introduced.
Usage of the %W command:
Prior to every scheduled frequency change the external scanner must send a %W[0]
command to the PTC: (Parameter 0 is optional but should be given in order to make sure
upward compatibility.)
%W[0]
Possible response of the PTC: 0 or 1.
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