B&B Electronics 3PCI2 - Manual (Page 56)

Documentation Number 3PCI2-0903 Manual Chapter 7 51
B&B Electronics Mfg Co – 707 Dayton Rd - PO Box 1040 - Ottawa IL 61350 - Ph 815-433-5100 - Fax 815-433-5104
B&B Electronics Ltd – Westlink Comm. Pk. – Oranmore, Galway, Ireland – Ph 353-91-792444 – Fax 353-91-792445
Fig. 7.3 RS-485 Connections for 2-Wire Mode
8. To check 2-wire RS-485, you must either enable the receiver
by moving the receive jumper to RX ENABLE mode (Table 1),
or use one port to transmit to another by cross connecting (Fig.
7.3) 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.
9. 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.
10. Try another software package for troubleshooting.
11. Check our website for available FAQ's or troubleshooting hints.
12. Contact B&B Electronics Technical Support for troubleshooting
assistance.
USA Office
Technicians are available at (815) 433-5100 to answer your
questions from 8 AM - 5 PM weekdays (Central Time).
Email: <[email protected]>
European Office
Technicians are available at +353 91 792444 to answer your
questions from 8:30 AM – 5 PM weekdays (GMT Time).
Email: <[email protected]>