Strange vk204-25

[nrousselca]

This vk204-25 (rs232) was running in the field for more thant one year. It recently start to react slangly. It was install (as many others here) as is with the original MATRIXORBITAL setings including the spash screen. Since a few days ago the start screen switch to all kind of characters with no communication. It was replace with an other one without any problems.

The so said defective unit was sent to me to check what could be the cause (our systems or the unit itself). This faulty unit now respond to and only to 2400 baud no matter what we try. Manually overriding it reset the default setting without saving them with Set Remenber active (254,147,1).

Procedure used:
1-powering the unit with the override jumper,
2-Setting the Remenber active (254,147,1),
3-Changing the Baud rate to a different baud rate,
4-Setting the Remenber active (254,147,0),
5-Recycling the power with no override jumper.
The baud rate remains at 2400 baud ?

Thanks helping me with this one.

[Clark]

Hi There,

Sorry to hear you've been having some communication trouble with an older VK204-25 unit. I have a couple questions below that will help clarify the problem, if you could please provide any answers as you are able.

First, your procedure looks alright, but I'd just like to confirm that communication is alright before commands start getting sent, something like text or backlight commands will provide verification. Also, I'd like to see the baud rate command used; there are slight differences in our lines so I'd like to confirm the speed byte to be correct.

One other measure when resetting will be to set and save the data lock to an unlocked state between steps one and two. It seems like many settings have been changed and the lock may be one of them. Have a look in your manual for that command, if available I believe it will look something like 254 203 245 160 0.

Thanks,
~Troy

[nrousselca]

Changing the capacitors around the ST202 chip solved the problem. I do remember having this kind of issue before with a surface mount cap and a RS232 driver. (??)
Thanks