Data Sheet

dScript

dScript User Manual v2.15

Digital IO

Our Ethernet modules could potentially have many types of outputs. For example the ETH008

only has one type - Relays. The dS3484 & dS1242 have both Relay outputs and NPN Open

Collector Transistor outputs. Activating a relay means turning the relay on. Likewise activating

an output means turning the transistor on. This will cause it to sink current to 0v ground. If

you had an LED connected from the output to 12v (via a resistor of course) it would light up.

Other modules (not this one) could have PNP Open Collector Transistor outputs. These types

will source current from the supply when active.

So here's the point: Active does not mean a high voltage comes out. It means that the output

has been activated. That could result in the output sinking or sourcing current, depending on

its type. The outputs will sink current (up to 200mA max.) when active.

The same principle applies to the inputs, these are designed to allow you to directly connect a

VFC (Volt Free Contact). This could be from other relay contacts, thermostat contacts, alarm

contacts etc. When the contacts are closed the input will read as active. In fact anything that

pulls the input pin down to 0v will read as active. Do not think of the I/O in terms of a high or

low voltage output. Think of it in terms of Active (or on, something is actively driving the I/O),

or inactive (or off, nothing is driving the I/O). It's a subtle point but one you need to be clear

on.

Example input - connecting a

switch

Connecting a simple switch could not

be easier, just wire the switch

between a pin (P) and ground (G).

When the switch closes the input will

become active.

Example output - connect a relay

You can connect your own 12V relays

(200mA max), the first coil pin of the

relay is wired to the 12V supply

terminals on the board, the other is

wired to the output pin (P). When the

output pin becomes active it is driven

down to 0V ground, the relay will

have 12V across the terminals and

switch so COM is connected to NO.