User's Manual

Page 30

M Series Data Radio – User Manual

Part E – Getting Started - EB450

Digital Inputs and Outputs

The EB450 provides a facility for two channels of digital user inputs

and outputs (Digital User I/O). Information on how to control and

monitor this I/O using TVIEW+ Diagnostics can be found in the E

Series User Manual - Part J - TVIEW+ Management Suite - Remote

Diagnostics & Network Controller.

All user I/O is optocoupled for isolation between the EB450 and uses

equipment. When using the I/O facility the I/O electrical characteristics

and ratings must be observed. Failure to observe these ratings may

result in equipment damage.

Inputs

Two User Inputs are available. They have identical interface

characteristics. Each input has an internal resistance of 470 Ohms.

Some form of switching contact (ie: switch, relay) is normally used to

change the state of the input. Both an isolated and non-isolated input

configuration is possible.

Typical Radio Setup

TVIEW+ Diagnostics will recognise an input as being ON when the

switch is closed. If the switch is open (or not connected) TVIEW+

diagnostics will recognise the inputs as being OFF.

Outputs

Two User Outputs (Open Collector) are available. They have identical

interface characteristics. The maximum current allowed through each

output is 20ma. External resistors must be used keep the current

below this value.

Each output has an internal resistance of 100 Ohms.Ohms law can be

used to calculate the resistance required for a specific voltage (keeping

the current below 20mA). Nominally 1k Ohm is used for a +13v8

supply and 330 Ohms for a +5v supply.

When the OUTPUT is OFF, V = Vs. No current will flow when output

is off.

When the OUTPUT is ON, V = nominally 2.3 volts . Current is set

by resistor.