Appendix B - Data Exchange Interface - Graco CGM Instructions And Parts

Appendix B – Data Exchange Interface
This is bi-directional interface which provides both transmit and reception of data between the HFR/ NVH system, and the
controlling logic (PLC, robot or equivalent). The interface allows a large amount of data to exchange between the
systems, while only occupying a very small portion of the map to support the exchange. The interface also allows for
future expansion of data without changing the map structure.
To get, receive or read data from the HFR/ NVH system, the controlling PLC needs to:
1. Write to the "Data Exchange Interface – Data Pointer Command" location on the map (output bytes 20 – 21, O160
– O175) a value corresponding to the data the PLC wants to receive.
Wait for the HFR to provide the same "Data Exchange Interface - Pointer Last Serviced " number written in the
2.
previous step at input byte locations 26 – 27 (I208 – I223).
3. Read the requested data at input byte locations 28 – 31 (I224 – I255), "Data Exchange Interface – Input Data
Element".
To write or transmit data to the HFR system, the controlling PLC needs to
A. Write the data for the HFR system to "Data Exchange Interface – Output Data Element" location, output byte
locations 22 – 25 (O176 – O207).
B. Write to the "Data Exchange Interface – Data Pointer Command" location on the map (output bytes 20 – 21, O160
– O175) a value corresponding to the data the PLC wants to transmit to the HFR.
C. The HFR will echo back to the PLC the "Data Pointer" and the "Data Element " after the HFR system processes
the data transmit request to input locations 26 – 27 (I208 – I223), and input locations 28 – 31 (I224 – I255)
respectively.
Note 1: When changes are made over the data exchange interface, the HFR/ NVH system display screen may not
update immediately. It may be necessary to navigate away from the screen then back to it, or a new dispense may need
to be triggered.
Note 2: All Read designations on the Data Exchange are assigned and Even numbers, whereas all Write designations
are assigned an Odd number assignments.
CGM Interface Manual, HFR/ NVH (Small Map with Data Exchange) Applications, March 25, 2022, Page 12 of 23