SC4000 REFERENCE MANUAL
5
SGND RXD
TXD
CTS RTS
USER INTERFACE
SGND TX
RX
RTS CTS
SC4000
Figure 16 – RS232 Host Interface Connections Using Hardware Handshaking
The RTS and CTS signals control data transmission and synchronize the connected devices.
START
OF
TRANSMISSION
END
OF
TRANSMISSION
+ V
RTS
- V
+ V
TX DATA
- V
+ V
CTS
- V
DATA
TRANSMISSION
DATA
TRANSMISSION
C1 C2
C4
C3
C5
TRANSMISSION
STOPPED
ENABLED
DISABLED
ENABLED
IDLE
IDLE
Figure 17 - RS232 Control Signals
If the RTS/CTS handshaking protocol is enabled, the SC4000 activates the RTS output to
indicate a message is to be transmitted. The receiving unit activates the CTS input to enable
the transmission.
RS485 Full-Duplex Interface
The RS485 full-duplex (5 wires + shield) interface is used for non-polled communication
protocols in point-to-point connections over longer distances (max 1200 m / 3940 ft) than
those acceptable for RS232 communications or in electrically noisy environments.
The pinout table follows:
Pinout
Function
TX+
RS485 Transmit Data +
RX+
RS485 Receive Data +
TX-
RS485 Transmit Data -
RX-
RS485 Receive Data -
SGND Signal
Ground
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