Peripheral Devices
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How to map input and outputs
The mapping between the areas inside the PowerMACS PLC and the external communication device
addresses are as follows:
For the EXTCOM_in/out driver
For the EXTCO2_in/out driver
How much of the respective areas to use for inputs and/or outputs is set up using the drivers as explained
below. Please note that if an area is used for both inputs and outputs the outputs must be located directly
after the inputs.
Example:
Note! All numerical values are written and read as Big Endian values (commonly referred to as Motorola
format).
8.13.3 Access to Process data
The external device accesses the Process Data areas by normal read and writes accesses.
Since Process Data quite often is bigger than what can be transferred using a single read or write
operation all process data handling are done by splitting up each process data item into smaller parts
called packages. Each access will transfer a new package. The external device must then put the
packages together to recreate the original data. How to do this is described in chapter: Process data.
8.13.4 Serial Communication Protocol Information
Serial communication devices use serial protocols to communicate with PowerMACS. Chapters below do
not describe the protocols in full detail but gives a brief description of major characteristics and how they
are used with PowerMACS.
The communication is for all protocols based on simple read and write operations. Examples of character
flow is included for two types of communication:
ï‚· Read five integers at address 500..509, i.e. PLC outputs area, address 2500..2509
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