stamp to sonar device

Archiver

Jeff-

At 19.2K baud, the six bytes returned from your device may be
transmitted in as little as ~3.125 msec. Make sure you're looking
for them _immediately_ after you send your six bytes and avoid any
fancy stuff in the way they're received.

When you send from the laptop, are you sending parity bits (is the
device expecting parity bits)?

Are you sending inverted or non-inverted from the Stamp? As I
understand your setup, you would want non-inverted (mode 110) going
into the TTL->232 converter/inverter.

Maybe if you were to post a few pertinent lines of your code somebody
would see a problem.

Can you tried directing the device's output to your laptop to see if
something really is coming back but the Stamp just isn't catching it?
Or the reverse--send from the laptop and receive on the Stamp? Maybe
a variation will tell you something.


Regards,

Steve

Archiver

We are having one heck of a problem with a basic stamp 2sx. Our main
objective is to communicate with a Massa sonar device. The device is
expecting 6 bytes sent in 13.5 ms. We prototyped this on a laptop
with no problem. When we changed to the stamp we get nothing back
from the sonar device. This is how it is setup.

Using a MAX232 chip from TI we have hooked it up according to
datasheet instructions.

We have a stamp 2sx hooked up to use P8 as the output and P7 as the
input.

The total hookup is as follows: (pin settings of 19.2k,8,1)

Stamp => MAX232(TTL-RS232) => RS-232/RS-485 Converter => Sonar Device

When we hook up as follows

Laptop RS-232 => MAX232(RS232-TTL => TTL-RS232) => RS-232/RS-485 =>
Sonar Device

And send the 6 byte request for status message we get back an answer
of 6 bytes. (the right answer)

When we hook up using the stamp and have the stamp send the 6 bytes
nothing happens.

I am guessing maybe a grounding problem as the Sonar and the Stamp
board are running on different power supplies.

Thanks

Jeff