Simple IO Protocol - turag-ev/TURAG-Feldbus GitHub Wiki

Simple IO protocol supporting binary and 16 bit analog in-/outputs (originally named ASEB protocol).

The first byte of a packet (address) and the last (checksum) are left out in all packet descriptions/representations on this page.

Overview

A maximum of 16 channels are supported for each input and output type, the exact number can be set.
An index is assigned to each channel.
All input values are read out at once with the Sync command.
Outputs are set with separate commands.
Setting initial values is error-free by definition - the device should ensure that this is fulfilled.
Outputs can have an initial value other than 0. Therefore it is possible to read the status of outputs.

16-bit values are transmitted as Little Endian.

IO type	Index range	Description
Digital Inputs	1-16	Transmitted as a 16-bit bit mask regardless of the exact number.
Analog Inputs	17-32	Signed 16 bit values.
Digital Outputs	33-48	Transmitted as byte value.
Analog Outputs	49-64	Signed 16 bit values.

Basic commands

Name	Request	Response
Sync	`<0xFF>`	`[<digital inputs if at least one available, 2 byte>][<1. analog input, 2 byte>][<2. analog input>][...]`
Set digital output	`<Index><Byte>`	`<empty packet>`
Set analog output	`<Index><Low-Byte><High-Byte>`	`<empty packet>`
Read digital output value	`<Index>`	`<Byte>`
Read analog output value	`<Index>`	`<Low-Byte><High-Byte>`

Extended commands

Commands to query information about the available channels. The request always consists of one byte with the command + possibly the index of a channel. The answer is usually a number with a length between 1 and 4 bytes.

Command	Command Key	Channel index required as 2. byte?	Response length
Length of a Sync Response	0xF4	-	uint8
Number of digital inputs	0xF7	-	uint8
Number of digital outputs	0xF8	-	uint8
Number of analog inputs	0xF9	-	uint8
Number of analog outputs	0xFC	-	uint8
Length of channel label	0xF6	yes	uint8
Channel label	0xF5	yes	variable