DocumentationNumber 3PCI2-0903 Manual Chapter6 45
B&BElectronics Mfg Co – 707 Dayton Rd - PO Box 1040 - Ottawa IL 61350 - Ph 815-433-5100 - Fax 815-433-5104
B&BElectronics Ltd – Westlink Comm. Pk. – Oranmore, Galway, Ireland – Ph +353 91-792444 – Fax +353 91-792445
4-Wire RS-422 or RS-485 Connections
Figure 6.2
Note: With RS-422 Devices, connect only one device to computer.
Connect the TD(B) pin #2 on the computer to RD(B) on the device.
Connect the TD(A) pin #3 on the computer to RD(A) on the device.
Connect the RD(B) pin #9 on the computer to TD(B) on the device.
Connect the RD(A) pin #1 on the computer to TD(A) on the device.
Connect the Signal Ground pin #5 to Signal Ground on the device.
In a 4-wire RS-485 system, each receive line connects to the same
receive terminal on all slaves, and each transmit line connects to the
same transmit terminal on all slaves. The master to the first slave is
connected as above.
In a multi-slave RS-422 connection, TD(B) and TD(A) connect to
RD(B) and RD(A) on all the slaves. If the slaves have Transmit
connections, only one device can be connected back to the master.
See Fig. 6.3 on next page
.