Devantech ETH8020

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Mapping inputs to custom devices

Sometimes it is useful to have a message sent on input change without the need for polling, you can use the input

mapping for sending messages to an IP address. The transactions are described below along with an example of the

custom device needing a password of “apple” and setting output number 1 active:

• The ETH8020 sends a TCP packet with 0x79 (password entry) in the first byte, then the following bytes will be

the password supplied above.

So it would send 6 bytes: 0x79, 'a','p','p','l','e'

• To acknowledge a password match, respond with 1, else send 2

You reply with 1 byte 0x01

• The ETH8020 sends then sends digital active (0x20) or digital inactive (0x21) followed by the output number

So it would send 2 bytes 0x20, 0x01

• Reply with a 0 for success, else send 1

You reply with 1 byte 0x00

Note that the complete sequence must be followed, even if the password fails. If no password is supplied in the input

mapping configuration the sequence will be followed with the absence of ''a','p','p','l','e' bytes.

Input monitoring example and source code

We have an example of mapping the inputs to a PC, it operates on the default port of 17494, the default password of

"password" (although both are easily changed in the source code) and requires the ETH8020 input mapping to be

pointed at the host PC IP address. As it's having to constantly listen it's a multi thread program

The input monitor program is available as Visual C# express ready built installation files here, or as project with source

files here. Visual studio express is provided free from Microsoft: http://www.microsoft.com/exPress/download/

HTML commands DOAx and DOIx (V5+ firmware needed)

A customer requested feature, allowing the digital outputs to be switched by the Http get function such as used in some

voice over ip phones (VOIP). You can use the Http get function to write to the io.cgi file with the following syntax:

192.168.0.200/io.cgi?DOA2=10

This would use the default address (192.168.0.200) and make output 2 active for 1 second.

Another example would be to set output 1 inactive for 10 seconds:

192.168.0.200/io.cgi?DOI1=10

You can test these functions by typing them directly into the address bar of most internet browsers. Also be aware that

you may need to disable Http authentication in the Http configuration if your control device does not support it.

Devantech ETH8020 - Page 8