Powered converter vs port powered converter

[Hema Tanikella]

I want to communicate with a Diamond Camera using KD-6 protocol. I am using a RS 485-RS232 port powered converter and the command doesnt seem to be going to the camera. Shud I use a powered converter or a port powered converter and what is the difference.

[Ray K]

Port powered converters draw power from the handshaking lines and usually cannot transmit over longer cable lengths. So a powered converter is better. However, you may not need to change your converter at all. You should do a loopback test to test your converter first.

Serial Loopback Tutorial General information and how to do Hyperteminal Loopback test.
http://zone.ni.com/devzone/conceptd.nsf/webmain/D48BA43C59B60277862569EE000501FD?opendocument

[Tom_Hawkins]

Is it a two-wire or four-wire RS-485 connection? For a two-wire connection the converter must disable its transmitter after sending data in order to receive the reply from the remote device. Some (cheaper?) converters use the state of one of the RS-232 status lines to control when the transmitter is switched on, and you may not be able to control this line using the LabVIEW serial or VISA VI's. If this is your problem, the solution is to look for a converter that is auto-gating, i.e. switches from transmit to receive automatically when you stop sending data.