Here is what I found....probably not helpful, but data points at any rate.

Connected to the FT-60, on download I see RTS/CTS (connected together) go high, that is important as it powers my interface.  Then a good stream of data as it is downloaded.

On upload, I see RTS/CTS go high, then one short data burst, maybe a couple of characters, then the error pops up and data stops and RTS/CTS goes low.

I did one other thing, I loaded the program on my Macbook Air.  I got the same results, I can read the FT-60 but not write it.  I can read and write the FT-8900 on the Macbook same as on the PC.

It could be the Chirp software, or it could be hardware.  But, as far as the hardware, it doesn't make sense that the FTB60 will work ok. 

Suggestions anyone?

Bob -N4RFC

On 2016-04-26 21:24, Tom Hayward wrote:

On Tue, Apr 26, 2016 at 1:20 PM,  <bob@n4rfc.com> wrote:

However, I loaded a copy of the FTB60 program from G4HFQ, imported a CSV file from the 8900 and the FTB60 program wrote the FT-60 first try. So, I think the levels are probably good between the radio and the interface. I will look at them on the O-Scope just to make sure.

That is pretty definitive, and I don't know that the o-scope will tell
you anything more at this point. It might be interesting to compare a
serial data capture from Chirp and FTB60 to see if there is a
significant difference that could explain the problem with Chirp. I
don't know how to help you with the serial capture -- I have only used
portmon on 32-bit Windows. I hear it's incompatible with 64-bit
varieties.

Tom KD7LXL