Fighting with computers

Computers are not always friendly.

Saturday, February 04, 2006

Breaking your nerves

Dealing with software you cannot change is a risky business. This time I need to emulate a serial communication to fool the software to think it is talking to a directly connected device. I have tested several serial port emulation software with not much luck. However I have to tell you the guys at Fabula Tech have a winner with their Network Serial Port Kit. It worked like a charm, providing a way of sharing a serial port on one computer so a second computer could use it remotely through a network connection. Not only this, but these guys have a fantastic on-line support chat that, contrary to most of them nowadays, they are knowledgeable and they solved my problem at the first shot. Really recomended product and service.

However, I needed a solution I could throw at a client's computer even without network card. I looked around for serial device servers and Digi One SP looked a good choice. I bought a couple of units to see if they could really replace a serial cable (you replace a 3-meter serial cable costing $6 for around $300 of electronic equipment, ... don't tell this to my boss). The point was that by doing this I could check if those devices behaviour was transparent enough for my application.

In short, it didn't work. Again, I could experience a quite good customer support service too. But unfortunately, after several messages exchanged they concluded what I needed was not possible. The problem? Well, my serial connection started with a sequence of break conditions. The software running on the PC waited for these breaks to be received and it created a long break condition in response. The Digi One SP units do forward break conditions to the other end, but they are fixed length (actually you need to talk to the tech support first, as the set line break=send range=1 does not appear anywhere on the product documentation). I needed the units to create an exact copy of the duration of those break conditions so it did not work.

What it did work was when I installed the RealPort(tm) driver supplied with the Digi One. It's a driver that adds a virtual serial port to your computer. You point the driver to the Digi One IP and you can use it as an additional serial port from your computer. With this setup breaks are the right width and everything works ok. I even get this new virtual port to work with Dynamic C to talk to a Rabbit RCM3700 core module. So if you need an extra serial port I recomend you to get a USB-serial dongle, but, if you have $150 to spare (or no USB but a network connection) then get a Digi One.

1 Comments:

  • At 9:31 am, Blogger Hiroshi Ikeda said…

    I have a commentary about on-line support service of The Imaging Source.
    After 3 mails specifying that their cameras have a random behaviour relative to triggering issues, they told me 3 times that it isn't possible, and that we have not a stable trigger signal. Well, mailing people like that is a time waste. You had luck in custumer support, that's unsual. Good luck with this tricky project!!!

     

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