writelog的帮助,cw interface部分有说明:
writelog also puts the ptt signal on the rts line of the same comm port. writelog allows you to use the same comm port for both cw and for rig control, but you will have to build your own y cable that sends the appropriate wires (txd, rxd) to the rig control port and the appropriate wires (dtr, rts) to your cw and ptt circuits.
就是说,你计算机的只使用一个串口,分别引出两组线,txd、rxd、gnd用于连接电台数据接口、dtr/cts、gnd用于连接cw接口。
这就是所谓的y cable。