StarTech.com IC485SEU - Manual (Page 5)

7 4
Multidrop
Multidrop configuration means that more than two devices can be linked all together to
communicate to one another through many IC485S / GB / EU devices. In this
configuration, one of the IC485S / GB / EU devices will be connected to a master device
and the rest of the IC485S / GB / EU devices will be connected to many other slave
devices.
Note: Bn means any one of the B1, B2, B3 and so on.
Monitor Mode
Monitor configuration means an IC485S / GB / EU device can be wired to the lines of
RS-232 or RS-422 devices to monitor the line signals. In this configuration the IC485S /
GB / EU will change the function of the T+ and T- to R’+ and R’- respectively.
Before operating, the user must complete the installation according to the
procedure mentioned.
Once the installation has been done, the device should operate as the setting function.
Note: R+ and R- signals are converted and linked to the RS-232 port and DB25 pin 3.
R’+ and R’- (T+ and T-) signals are converted and linked to the RS-232 port DB25 pin 2.
Note: The RTS must be at the low level in monitoring mode.
PC1
COM1/
COM2
T+
T-
R-
R+
IC485S
=>
A
PC2
COM1/
COM2
R+
R-
T-
T+
IC485S
=>
PC3
COM1/
COM2
=>
PC4
COM1/
COM2 =>
B1
R+
R-
T-
T+
IC485S
B2
R+
R-
T-
T+
IC485S
B3
Device
A
B SW1
DCE/DTE
DCE/DTE SW2
TxON, RxON
TxRTS, RxON
T+
T-
R-
R+
Device 1
R+
R-
T-
T+
PC
COM1/
COM2 =>
Device 2
T+ (R'+)
T- (R'-)
R-
R+
IC485S
A
Device
A SW1
MONI SW2
TxRTS, RxON
Multidrop/4-Wire
Full Duplex
Configuration
Monitoring
Configuration