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UNO-4678 User Manual 12

2.2.4 RS-232/422/485 Selection

COM1 ~ COM8 support RS-232, RS-422 and RS-485 interfaces. The

system detects RS-422 or RS-485 signals automatically in RS-422/485

mode.

To select between RS-422/485 and RS-232 for COM1 ~ COM8, adjust

JP3 ~ JP10.

Jumper settings for RS-422/485 interface: (JP3 ~ JP10)

Figure 2.3: RS-422/485 jumper setting

Jumper settings for RS-232 interface: (Default setting) (JP3 ~ JP10)

Figure 2.4: RS-232 jumper setting

2.2.5 Auto Flow Control & Master/Slave Modes

You can set the “Auto Flow Control” mode of RS-485 or “Master/Slave”

mode of RS-422 by using the SW2 DIP switch for each RS-422/485 port.

In RS-485, if the switch is set to “Auto”, the driver automatically senses

the direction of the data flow and switches the direction of transmission.

No handshaking is necessary.

In RS-422, if DIP switch is set to “On,” the driver is always enabled, and

always in high or low status.

2.2.6 Termination Resistor (JP1 ~ JP8)

The onboard termination resistor (120 ohm) for COM1 ~ COM8 (J1 ~ J8)

can be used for long distance transmission or device matching. (Default

Open.).

COM Close A Enable TR for Data/TX

Close B Enable TR for RX

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