RS485: testing loopback

No, it won't work.

You can test local loopback - verifying that your hdx connection is OK at your 485 converter. But you can't force the loopback to occur at the far end of the line, so if the cable to your destination is broken, you won't know. For this reason, most 485 hdx implementations have the remote slave devices issue an acknowledgement message of some kind whenever they receive something (valid) from the master. If the software loopback works, then the hardware is confirmed.

Steve

Looks good, try it. You might need to switch to full duplex for loop back. Don't know if your module will receive while transmitting which is required for the loopback, in half duplex mode.

Some ICs disable the rx when transmitting in half duplex mode.

back.

So how do i check the o/p? I can check it with scope. But I need to test it through s/w. Is there any way? I have this ready converters with DB-9 connectors on either side.