Mapping IW and QW addresses

General

Mapping input/output data addresses is used to achieve the clearest possible addressing.

A slave can be made up of several modules of different data sizes. In this case, misalignment of addresses can happen.

To avoid this, modules can be physically positioned in the slave rack by:

grouping together input modules of a particular size (e.g.: 1 byte) for each pair,
grouping together output modules of a particular size (e.g.: 1 byte) for each pair,
positioning a single input module of a particular size (e.g.: 1 byte) at the last input module position,
positioning a single output module of a particular size (e.g.: 1 byte) at the last output module position.

Example: non-mapped modules

Slave x in non-mapped modules

Module A

1 input word

Module B

1 input byte

Module C

1 output byte

Module D

1 input word

Module E

1 output word

Module F

1 output byte

Input image

%IWr.m.0.d	%IWr.m.0.d+1		%IWr.m.0.d+2
Module A 1 input word	Module B 1 input byte	Module D 1 input word		Unused byte

Output image

%QWr.m.0.d			%QWr.m.0.d+1
Module C 1 output byte	Module E 1 output word			Module F 1 output byte

Example: mapped modules

Slave x in mapped modules

Module A

1 input word

Module D

1 input word

Module B

1 input byte

Module E

1 output word

Module C

1 output byte

Module F

1 output byte

Input image

%IWr.m.0.d	%IWr.m.0.d+1	%IWr.m.0.d+2
Module A 1 input word	Module D 1 input word	Module B 1 input byte		Unused byte

Output image

%QWr.m.0.d			%QWr.m.0.d+1
Module E 1 output word			Module C 1 output byte	Module F 1 output byte