DIP Switch / Mode Settings
Document Number 3PCI-0712m
Appendix A
A -1
3.
To check 2-wire RS-485 RS-422 or 4-wire RS-485 Loopback Connections,
you must either enable the receiver by moving the receive jumper to RX
ENABLE mode, or use one port to transmit to another 2-wire RS-485 port or
converter by cross connecting and loading ComTest twice, one copy for each
port.
Characters typed in one copy of ComTest will appear in the receive window of
the other. Note that software must ignore the RS-232 handshaking lines in
RS-422/RS485 mode, the input lines (CTS, DSR, DCD, RI) are not pulled
high.
4.
Some manufacturers label their data connections for A and B reverse of the
standard for RS-422 or RS-485, so that the A line is (+) and B line is inverted
(-) following the IC standard. In such a case, just swap the wires and try it. No
damage occurs in the RS-485 mode, just no devices will respond. The EIA
standard for signal labels defines the B line as positive relative to A during
the ―MARK‖ state.
5.
Try another software package for troubleshooting. Some applications try to
bypass the Windows drivers and access the hardware directly.
6.
Check the B&B website for available FAQs or troubleshooting hints.
7.
Contact B&B Electronics Technical Support for troubleshooting assistance.