Data Mapping with I/O Bases

Discrete I/O Bases

With discrete Momentum modules, each terminal I/O point is mapped according to the following principle:

Each is mapped to bytes (max 4 bytes for 32 inputs or 32 outputs).
The least significant byte (LSB) is sent or received first.
The bytes (output words) sent from the communications adapter to the I/O base represent the output values.

The bytes (input words) sent from the I/O unit to the communications adapter represent the input values and status statement.
The register addressing is compatible with standard TIOs.

The following message structure illustrates the data exchange between the master and the slaves (I/O modules) for 2 discrete I/O bases.

Byte No.	Significance	170 ADI 350 00 input data	170 ADI 350 00 output data
0	LSB	Inputs 8...1	Outputs 8 ... 1
1	-	Inputs 16 ... 9	Outputs 16 ... 9
2	-	Inputs 24 ... 17	Outputs 24 ... 17
3	MSB	Inputs 32 ... 25	Outputs 32 ... 25

The I/O bits are mapped via the bus as follows:

Analog I/O Bases

With analog Momentum modules, each terminal I/O value is mapped according to the following principle:

Each analog value is mapped onto one word.
The least significant word (LSW) is sent or received first.
The words (output registers) sent to the I/O base represent the output values and the parameters; the words (input registers) sent from the I/O base to the communications adapter represent the field values and status statement.
Analog value representation occurs in compliance with IDS 3000. Sign and value are flush left (nominal range is +/- 32,000) The resolution depends on the selected measuring or output range. Negative values are represented as double complements.

The following message structure illustrates the data exchange between the master and the slave (I/O module) for the 170 AMM 090 00 module

Word No.	Significance	Input data	Output data
0	LSW	Value, input channel 1	Parameter input channels 1 ... 4
1	-	Value, input channel 2	Parameter output channels 1,2
2	-	Value, input channel 3	Value, output channel 1
3	-	Value, input channel 4	Value, output channel 2
3	MSW	Discrete inputs	Discrete outputs

Further information is contained in the Momentum I/O Bases user manual.