Echoed response works in computer COM PORT but not in usb-rs232 connection

[jofruit]

Hey everyone,

I have been having peculiar issues in Labview related to my connections.  I am attempting to program on/off switches for the IP POWER 9258, a programmatically controlled power box (http://www.aviosys.com/downloads/manuals/power/9258st_en.pdf).  I have already built a successful VI that can be used with RS-232 connection to turn specific ports on/off based on .exe code.

Now here is the problem I face at hand.  I want to be able to check for errors such as disconnections with factors such as an empty returned string.  When I plug the box into the computer with a DB9 straight cable, I send commands and get replies confirming the commands.  When I plug it in via a Prolific usb-RS232 adapter, the operations work but the read does not.  I get a bunch of mumbo jumbo back (maybe emptying buffer) followed by no replies from the box on successful operation?  Does anyone know why this might be happening?  I have been using these adapters on 3 other devices and have been getting successful replies I expect.

Thank you

P.S.: I learned the RS232 interface here: http://koukaam.se/koukaam/downloads/NETIO-230_RS-232_control.pdf

[mikeporter]

According to the datasheet that you gave a link to, the device is programmed via the network interface using with HTML or Telnet. The RS232 interface appers to be for finding out some basic configuration info, but all the configuration examples use one of the other two protocols.

No idea why there is a difference between the two. Are you sure all the comm parameters are right?

Mike...

[Dennis_Knutson]

Write operations will seldom return any sort of error so you really don't know if those are working. I would suggest trying communicating with another program such as hyperterminal, putty, teraterm, or MAX. Checking to see if you have the latest prolific driver might be warranted.