# DAISY-18 - 4 channel industrial range optoisolated input (0-48 Volt)

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DAISY-18 is a four opto-isolated digital inputs board.
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<img src="./DAISY-18.jpg"/>

##Main features

* 4 input channels
* Max input voltage: 48 Volt
* Max input current: 
 * 15mA @ 24V
 * 18mA @ 48V
* Schmitt trigger input :
 * Low level input threshold: 10.5V
 * High level input threshold: 16V
* Isolation voltage: 2500 Vrms (max)

The daisy connectors where to plug this board are:

| Board  | Daisy Connector | 
|--------|-----------------|
| FOXG20 | D2    |
| FOXG20 | D5    |
| TERRA  | D11   |
| TERRA  | D12   | 

On the FOX Board G20 is requested a [Daisy-1](/DAISY-1) adapter.

## General Layout

The following picture shows Daisy-18 connectors and monitoring LEDs.

<img src="D18_Exp_01.jpg"/>

## Connecting to a Daisy-1

Up to 2 Daisy-18 boards can be connected to the same Daisy-1 connector by means of the Replicator connector J3. So full use of all I/O pins on a single Daisy-1 connector is made. This applies to Daisy-1 connectors: D2, D3, D5 provided all pins are set as GPIO.

Daisy-18 cascading feature is illustrated by the following picture :

<img src="D18_Exp_02.jpg"/>

## Different ways to connect a Daisy-18

The "floating" optoisolated inputs of the Daisy-18 handle the following configurations 

### Sink mode (aka NPN)

Up to 4 switches can be read in this configuration.

<img src="D18_Exp_03.jpg"/>

### Source mode (aka PNP)

Up to 4 switches can be read in this configuration.

<img src="D18_Exp_04.jpg"/>


Mixed modes are easily handled by Daisy-18 as shown in the following case list:

Case A

*	Input 1 : Sink mode
*	Input 2 : Sink mode
*	Input 3 : Sink mode
*	Input 4 : Sink mode

Case B

*	Input 1 : Sink mode
*	Input 2 : Sink mode
*	Input 3 : Sink mode
*	Input 4 : Source mode

Case C

*	Input 1 : Sink mode
*	Input 2 : Sink mode
*	Input 3 : Source mode
*	Input 4 : Source mode

Case D

*	Input 1 : Sink mode
*	Input 2 : Source mode
*	Input 3 : Source mode
*	Input 4 : Source mode

Case E

*	Input 1 : Source mode
*	Input 2 : Source mode
*	Input 3 : Source mode
*	Input 4 : Source mode

#Programming examples

Following there are some examples of code on how to use the Daisy-18 board.

Get the input state from one module: 

@pg='python/daisy18/read4.py' 

Get the input state from two modules wired on the same daisy connector: 

@pg='python/daisy18/read8.py'

## Schematics, datasheets and related links

*  [DAISY-18 Schematic](http://terzo.acmesystems.it/download/schematics/schematic_daisy18.pdf)
*  [ACPL-217 Photocoupler datasheet](http://terzo.acmesystems.it/download/datasheets/ACPL-217.pdf)
*  [Daisy modules and other boards available](/hqr)

@shop='DAISY-18'
@shop='FLAT-20CM'
@shop='DAISY-12'
@shop='IDC-PCB'