Appendix B - Data Exchanged
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Appendix B - Data Exchanged
The Data Exchange is a condensed structure used to read and edit a number of different variables in one data
location. If multiple data exchanges are needed, they must be cycled through.
Below is a timing diagram showing the Data Exchange portion of EFR CGM Map.
NOTE:
A 50ms delay is suggested between each CGM signal.
When the PLC needs to use the Data Exchange, the Data Exchange Element Desired must first be sent to the EFR.
Initially, the Data Exchange Element Selected and the Data Exchange Element Value are set to zero to signal the
data in the Data Exchange is invalid. Once the EFR returns the Data Exchange Element Value, followed by the Data
Exchange Element Selected, the PLC can compare the Data Exchange Element Selected to the Data Exchange
Element Desired and confirm the data is correct for the Data Exchange Element Desired. Once the Data Exchange
Automation Inputs are confirmed, the Data Exchanged Element Desired Value can be used to request a new value.
If the value supplied is within the operable range of the element, the EFR will accept the new value and will return
that value to the Data Exchange Element Value.
Automation Inputs (EFR Outputs)
Data Exchange Element Selected
Data Exchange Element Value
Automation Outputs (EFR Inputs)
Data Exchange Element Desired
Data Exchanged Element Desired Value
PLC State
Reading Sequence
Editing Sequence
Key
Duration that PLC can Read the information
Duration that PLC can Edit the information
EFR Data Exchange
Changing
Data
Elements
