Contec SPI-8550-LLVAS, User Manual

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4. Jumper Setting
36
SPI-8550-LLVAS
RS-232/422/485 Selector: JP6 & JP8
Table 4.6. RS-232/422/485 Selector
RS-232C
RS-422
RS-485
1. For RS-485, TX+(pin 2) and RX+ (pin 3) must jumper together
inside the D type connector.
2. TX- (pin 1) and RX- (pin 4) is the same.
JP6 JP8
JP6 JP8
JP6 JP8
(Default)
9 7 5 3 1
10 8 6 4 2
19 17 15 13 11 9 7 5 3 1 23 21
20 18 16 14 121 0 8 6 4 2 25 22
19 17 15 13 11 9 7 5 3 1 23 21
20 18 16 14 121 0 8 6 4 2 25 22
19 17 15 13 11 9 7 5 3 1 23 21
20 18 16 14 121 0 8 6 4 2 25 22
9 7 5 3 1
10 8 6 4 2
9 7 5 3 1
10 8 6 4 2
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 SPI-8550-LLVAS uses the RTS signal and bit 1 in the modem control register to control
transmit data.
Modem control register
(Setting I/O a4H) bit 1: 0 … RTS High (Disables transmission)
1 … RTS low (Enables transmission)