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4. Jumper Setting
26
SEH-9450-LAS
CF Master / Slave selector: JP1
On board CF slot is connected to Secondary IDE. This jumper is select Master/Slave of CF memory
card. Usually, please use it with a master setup.
Table 4.3. CF Master / Slave selector
JP1 Function
1
2
3
Set to Master
1
2
3
Set to Slave (Default)
RS-232/422/485 Selector: JCOM1
Table 4.4. RS-232/422/485 Selector
RS-232C
(Default)
JCOM1
19 17 15 1311 9 7 5 3 1
20 18 16 141210 8 6 4 2
RS-422
JCOM1
19 17 15 1311 9 7 5 3 1
20 18 16 141210 8 6 4 2
RS-485
JCOM1
19 17 15 1311 9 7 5 3 1
20 18 16 141210 8 6 4 2
1. For RS-485, TX+ (pin2) and RX+ (pin3) must jumper together inside the D type connector.
2.
TX- (pin1) and RX- (pin 4) is the same.
Transmit date control in half-duplex mode
In half-duplex mode, the transmission buffer must be controlled to prevent transmit data from causing a
collision. The SEH-9450-LAS uses the RTS signal and bit 1 in the modem control register to control
transmit data.
Modem control register
(Setting I/O address +4H) bit 1: 0 … RTS High (Disables transmission)
1 … RTS low (Enables transmission)