At 12:30 +0000 02/13/2004, Craig Graham wrote: >The next is in the other port settings. The manual specifies 1 start bit, 8 >data bits, 1 stop bit, no parity. The VISA serial stuff in Labview 7, which >I've only just started playing with, has properties for stop bits, data bits >and parity which I've set, but I can find no option for start bits. Is this >a problem? On the offchance, I've tried all three numbers for "stop bits" >with no success. One start bit is the only option. I have never seen a device that uses a different number of start bits. But serial is so screwed up I am sure there is someone out there that decided to use pi start bits!
>The bytestream can contain null characters, so I've found the "Discard NUL" >property and switched it off. Since it's three wire communication- ground, >rxd and txd, I've set handshaking to none. I've also disabled the >termination character. > >Again on the offchance, I've tried sending an additional null byte at the >end but it didn't help. > >Does anyone have any suggestions? It seems that your device is not responding because it probably hasn't gotten a "complete message" from the host. Check the documentation to see if there is a message terminator in the command string? Try a carriage return or lf as a terminator. Try EOT as a terminator. Make sure that the string has the correct check sum (sometimes protocols have the checksum include the string lenght tag, sometimes not). I would guess the problem is in carefully crafting the string since you have tried all the hardware options. Many systems have a way of snooping on serial port communications. I can give you a good way for Mac OS X...... But I am going out on a limb and guess that isn't your host system! :-) Others can suggest software for various winders versions. -Scott
