Specifications

RS-232/422/485 2-PORT PCI CARD, OPTO-ISOLATED

RS-485 interface. The RTS mode uses the RTS modem

control signal to enable the RS-485 interface and

provides backward compatibility with existing software

products.

Figure 3-6. RS-485 Enable modes.

The RS-485 Echo is the result of connecting the receiver

inputs to the transmitter outputs. Every time a character

is transmitted, it is also received. This can be beneficial if

the software can handle echoing (that is, using received

characters to throttle the transmitter) or it can confuse

the system if the software does not. Position 9 of SW1

and SW2 is used to control the RS-485 enable/disable

functions for the receiver circuit. To select the No Echo

mode, place switch position 9 to the On position (see

Figure 3-5).

RS-232/422 Default

RS-485 Auto Enabled

SW4

SW3