7.1 RTS/CTS Handshake

Transmission of RTS, combined with reception of CTS, allows for hardware handshaking (data flow control) between the UART and the external device. RTS is transmitted on AUXOUT by connecting pins 4 and 5 of the jumper block. CTS is received on AUXIN by connecting pins 1 and 2 of the jumper block. If RTS/CTS handshaking is not desired, the RTS output can be looped back to the CTS input by connecting pins 1 and 4 of the jumper block. Figure 19 shows how to select the RTS/CTS mode.

Jumpers J5, J7

XCLK 6

3

RCLK

XCLK 6

3

RCLK

AUXOUT 5

2

AUXIN

AUXOUT 5

2

AUXIN

RTS 4

1

CTS

RTS 4

1

CTS

Transmit RTS on AUXOUT

Loopback RTS to CTS

Receive CTS on AUXIN

 

 

 

Figure 19 --- RTS/CTS selection

7.2 RCLK

This is the clock signal used by the receiver portion of the UART. It is generally provided by connecting it to the UART's own transmit clock output (XCLK). This is done by connecting pins 3 and 6 of the jumper block. If desired, RCLK can be received from an external source over the AUXIN line by connecting pins 2 and 3 of the jumper block. Figure 20 shows how to select the RCLK mode.

Jumpers J5, J7

XCLK

6

3

RCLK

XCLK

6

AUXOUT

5

2

AUXIN

AUXOUT 5

RTS

4

1

CTS

RTS

4

3RCLK

2AUXIN

1CTS

Loopback XCLK to RCLK

Receive RCLK on AUXIN

Figure 20 --- RCLK selection

26

DSCLP/SSCLP-200/300 User's Manual

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Quatech RS-422 user manual RTS/CTS Handshake, Rclk