[RTTY] CAT control on a Kenwood TS-870

[Vince]

I sent this out yesterday with no text, and had several interesting 
reply's, but not the one I was looking for, so I will try again, maybe I 
will get it right this time.

What is the proper cable to use with CAT control on a Kenwood TS-870 ? I 
tried a serial cable and it is not working, using Writelog, I have the 
port and baud rate set OK. I am using a USB to Serial converter, could 
this be part of the problem? this setup worked before with a Kenwood 
TS-450.

I have used CAT control with my Icom radios with no problems, I am 
trying to help a friend with his Kenwood.

TIA
Vince, K6BIR