Friday, September 24, 2010

Serial addition

I installed a four port RS-232 serial card in my shack PC today. When I bought the computer earlier in the year I purchased and installed a two port serial card, thinking that would be enough. But it wasn't. You can never have enough serial ports if you want to interface with radios. With four, I can now have CAT control of both the K2 and the K3, the TNC connection to the Kenwood TM-D710 and one more which is currently controlling the PTT of the FT-817 for the EchoLink node but could be used for the control port of the Kenwood if I ever decided to use that for EchoLink. No more hassles with USB to serial adapters, and all my USB ports are free for things like sound cards. I don't know why people use laptops for shack computers, they provide far fewer options.

Needless to say, things did not go as smoothly as they could have done. I thought I could have COM2 for the K2, COM3 for the K3 which would be easy to remember. But Windows gave the ports the designators COM3, 4, 10 and 11. There's an option to reassign the port numbers but Windows claimed that everything from COM2 to COM9 was in use. By what, was my unanswered question.

In the end I decided to name the ports COM2 through COM5 as I wanted regardless of Windows' protestations. They did work, but finding out which port was which was a matter of attaching a radio to one socket, loading a program and trying all possible COM port numbers until it worked, as there was no logical correspondence between the numbering and the sockets on the back of the computer. Who said it was meant to be easy anyway?

Despite all this I managed to make a few contacts using JT65A on 20m including DU1GM, N0OB and K1CF, using 25W to the dipole.

Although I now have computer control of the K2 I don't have a sound card interface as I have cracked open the plastic case of the USB audio dongle and superglued the bottom half containing the PCB to the stripboard on which I will be building my homebrew SignaLink clone. Of course, now I have a serial cable connection between the computer and the K2 I don't need a VOX controlled interface, never mind an isolated one because the serial cable will bypass the isolation anyway!


Tregonsee said...

Windows has a long memory of a port ever being used. Virtual ports are particularly bad from that standpoint. However, as you have found, ignore the whining and with a reboot all will be well. Assigning two logical ports to one physical port is still a bad idea though. ;) I have a null modem termination, which basically straps TXD to RXD. I plug it into a port, then work through the logical port numbers with a terminal program until it echoes. If so, I label it and move on.

VE9KK said...

Good afternoon Julian, I too have added serial cards to my PC. Have run into the same troubles and I had to smile when you mentioned trying to find out which port was which...been there. Julian I recently purchased over E-bay an Edgeport device. You can hook up to 8 serial cables into it and then there is a USB cable into the PC. Have not had a chance to use it yet but have read it works great. This may be another option if you run out of card space in the PC.