ProSoft Technology MVI69L-MBS - Manual (Page 119)

MVI69L-MBS ♦ CompactLogix Platform Reference
Communication Module User Manual
ProSoft Technology, Inc. Page 119 of 154
January 6, 2014
Specific Example #1: Master is issuing Modbus command with FC 16 (with Float Flag: Yes)
to transfer Float data to Slave.
(Float specific module parameters)
Float Flag: "Y" tells the Master to consider the data values that need to be sent
to the Slave as floating-point data where each data value is composed of 2 words
(4 bytes or 32 bits).
Float Start: Tells the Master that if this address number is <= the address
number in "Addr in Dev" parameter to double the byte count quantity to be
included in the Command FC6 or FC16 to be issued to the Slave. Otherwise the
Master ignores the "Float Flag: Y" and treat data as composed of 1 word, 2
bytes.
(Modbus Command parameters)
DB Addr - Tells the Master where in its database is the beginning of data to
obtain and write out to the Slave device.
Reg Count - Tells the Master how many data points to send to the Slave. Two
counts mean two floating points with Float Flag: Y and the "Addr in Dev" => the
"Float Start" Parameter.
Swap Code - Tells the Master how to orient the Byte and Word structure of the
data value. This is device dependent. Check Command Entry formats Section.
Func Code - Tells the Master to write the float values to the Slave. FC16.