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DIGITAL AND OPTO PORTS CHAPTER 6

Page 20 RPC-30

Figure 6-1 Digital I/O

INTRODUCTION

Digital I/O lines ar e used to inter face with opto-module

racks, switches, low current LED's, and other TTL

devices. The RP C-30 ha s 24 of these lines a vailable

through J3. 8 of these lines are high current outputs,

capable of sinking 75 to 200 ma. Additionally, there are

4 opto-module sockets on the card itself.

On-car d opto-mo dule slots accept G4 and G 5 series op to

modules. G4 series opto modules are used to sense the

presence of AC or DC voltages or switch them.

Maximum switching cur rent is 3 amper es.

G5 series are optically isolated analog input or output

modules. The modules connect to thermocouples,

RTD' s, load cells, 4-20 ma current loops, and general

purpose voltage inputs. They can also output voltages

and currents. These modules are supported by the AIN

and AOT commands. Input modules return a number

from 0 to 511 in a manner similar to an A-D.

Conversion time is about 1 milli-second.

In addition to the 24 I/O lines from J3, the display and

keypad por ts can be used as digital I/O . Refer to

chapters 8 and 9 for more information.

WARNING:

Apply power to the RPC -30 before applying a

voltage to the digital I/O lines to prevent current

from flowing in and damaging devices. If you

cannot apply power to the RPC-30 first, contact

technical support for suggestions appropriate to your

application.

This chapter is divided into two sections. The first

section refers to the on-card opto rack. The second

section refers to the digital I/O port J3.

ON-CARD OPTO RACK

Description

The on-card opto r ack accepts the popular G4 series opto

modules (manufactured by Opto-22, Grayhill, and

others). These modules can switch AC or DC voltages

from 12 to 240 volts at 3 amperes. They can also sense

input voltages of the same type and range.

The RPC-30 also accepts the G rayhill G5 series. These

modules m easure voltage, current, therm ocouple output,

or RTD resistance and return it as a frequency.

Additionally, modules c an output a voltage or a current.

CAM BASIC supports the G5 series through the AIN and

AOT commands.

Installation

The G4 and G5 modules are installed in the same

manner as an opto rack. A screw at the top is used to

secure the module to the board. M odules may be

installed in any order and types can be intermixed.

A hole for a standoff nea r the modules is provided to

keep the board from bending during installation or

removal.

Input and output lines are fastened by the two position

terminal in front of the appropriate opto module.

Refer to the appropriate module data sheet for additional

hookup information.

G5 operation

G5 modules may be used as inputs or outputs. Output

modules m ust be installed on an externa l opto rack . Its

use as an input is discussed first.

Values from G5 m odules are returned using the AIN

function. The syntax is

A = AIN(slot)

The slot number is from 0 to 3 or 100 to 123,

corresponding to the position on the board or external

opto rack. T his function r eturns a n umber from 0 to

511, corr esponding to a resolution of 9 bits. The A IN

function takes about 1 ms to convert the input data.

1 2 ... 17 18 19 20 21 22 23 24 25 26 27 ... 37 38

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