Modbus Register Map - GE DigitalFlow GF868 Programming Manual

Chapter 1. Programming Site Data
Procedure Options
After completing the above steps, the meter returns to the
•
To continue programming the meter, refer to the menu maps in Appendix A and navigate to the desired menu.
Then, proceed to the appropriate section of this manual for instructions.
•
To leave the User Program and retain the previous settings, press
prompt. Any programming changes will be discarded and you will be returned to the data display.
•
To leave the User Program and return to measurement mode, press
prompt. Your programming changes will be entered into the meter's memory, and you will be returned to the data
display.

1.12.3 MODBUS Register Map

When equipped with the optional MODBUS output card, the GF868 flow transmitter can send flow data and diagnostic
information to a flow computer (or SCADA) serially, using a Gould-type RTU protocol. In this case, only the
MODBUS function command, 3 (read multiple registers), 6 (write multiple registers) is valid. The format for the data
exchange is as follows:
•
The send command (initiated by the host flow computer or controller) comes in the form:
[time delimiter]<Addr><3><First Register MSB>
<First Register LSB><Register Count MSB>
<Register Count LSB><CRC Low><CRC High>[time delimiter]
•
The response (initiated by the host flow computer or controller) comes in the form:
[time delimiter]<Addr><3><Byte count><Data.........>
<CRC Low><CRC High>[time delimiter]
The format for the returned data types is as follows:
•
Integer (16 bit Integer) <MSB><LSB>
1 Register - 16 bit integer
•
Integer (32 bit IntegerI) <MSB><LSB><LSB><LSB>
2 Register - 32 bit integer
•
Floating Point (FP) <EXP><MAN><MAN><MAN>
2 Registers - 32 bit IEEE floating point number
To request specific parameters from the GF868 using the MODBUS, the control system must enter the appropriate
register number. Only registers 1 through 90 are available for MODBUS communications, while registers 508 through
512 are used by the GF868 to store the MODBUS parameters. For details, see Table 4 on page 33.
Note: If you request Ch2 or AVE data from a 1-Channel meter, the values will all be zero.
32
. Continue as follows:
User Program
and then press
[EXIT]
and then press
[EXIT]
DigitalFlow™ GF868 Programming Manual (1-Channel)
at the SAVE
[F1] = NO
at the SAVE
[F2] = YES