System information

Opto 22 (Digital I/O) Interface

VSBC-6 Reference Manual Reference – 49

ACK

OWER

When jumper V7 is installed, up to 250 mA can be drawn from J10 pin 49 to power the Opto 22

interface rack or other external equipment. The power output is protected by a self resetting

circuit breaker.

Warning! If the I/O rack is powered by a separate external supply, the power jumper on the

I/O rack or jumper V7 must be removed.

IGNAL

IRECTION

The 16 I/O signals are divided into two 8-bit I/O ports. The direction of each port is controlled

by the DIRHI and DIRLO bits in the DCAS register (see page 42).

IGITAL

I/O D

ATA

ORTS

DIOHI (READ/WRITE) 00E7h (or 01E7h via CMOS Setup)

D7 D6 D5 D4 D3 D2 D1 D0

DIO15 DIO14 DIO13 DIO12 DIO11 DIO10 DIO9 DIO8

DIOLO (READ/WRITE) 00E6h (or 01E6h via CMOS Setup)

D7 D6 D5 D4 D3 D2 D1 D0

DIO7 DIO6 DIO5 DIO4 DIO3 DIO2 DIO1 DIO0

Table 26: Register Bit Assignments

Bit Mnemonic Description

D7-D0 DIO15–DIO8

DIO7–DIO0

Digital I/O Data — Data written to these register is driven onto the Opto 22

Digital I/O port signals when the port direction is set to output mode. When the

port is in input mode, these bits reflect the input state of the signal lines.

DIO = 0 Signal low (GND)

DIO = 1 Signal high (+5V)

Note! Opto 22 modules use inverted logic. An "on" module is a "0" logic level.