[Yaesu] FT990 serial interface weirdness

[Brian Smithson]

Greetings!
 
I'm having problems with serial comms to my FT990.
 
What I'm doing is trying to interface with my 990 
from Microsoft Access using the MSComm serial control. 
I've got it about 98% working, but one last thing is 
driving me crazy and I was wondering if anyone would
have a minute to help me out.
 
It has to do with reading the rig's frequency. I'm 
grabbing both VFO's and most of the time everything 
works great. There seems to be a region of frequencies 
in the 20m CW band that don't read right - when the 
radio says 14.121.00 the reading I get from the serial 
port is 13.972.52! This continues for a short range 
and then the readings are OK - 14.126.00 reads fine, 
and then 14.127.00 reads as 14.083.48.
 
I've examined the bit streams as best I can and it looks 
like the radio is sending 158C04 hex for both 14.121.00 
and 13.972.52! I tried the same frequencies in a
commercial logging program with rig interfacing features
(LOGic 5 - a great program) and they displayed 
correctly. I have no way to 'sniff' the bits LOGic is
reading to tell if they are different.
 
At first I suspected the MSComm control itself, but 
the error is so localized - I haven't been able to 
make it happen any where else - only the low-end of 
the 20m band!
 
Has anyone seen anything like this? Is some sort of
correction required? Any ideas at all?
 
Thanks so much!
 
73, Brian n8wrl

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