Operating instructions

Modifying the Configuration File PTQ-MCM ♦ Quantum / Unity Platform
Modbus Communication Module
ProSoft Technology, Inc. Page 75 of 139
April 29, 2008
Master is issuing Modbus command with FC 3 to transfer Float data from Slave.
Float Flag: Not applicable with Modbus Function Code 3.
Float Start: Not applicable with Modbus Function Code 3.
DB Addr - Tells the Master where in its data memory to store the data obtained
from the Slave.
Reg Count - Tells the Master how many registers to request from the Slave.
Swap Code - same as above.
Func Code - Tells the Master to read the register values from the Slave. FC3.
Addr in Dev - Tells the Master where in the Slave's database to obtain the data.
In the above example, the Master's Modbus command to transmit inside the
Modbus packet will be as follows.
Slave address Function Code Address in Device Reg count
DEC 01 3 6100 2
HEX 01 03 17 D4 00 02
In the above example the (Enron/Daniel supporting) Slave's Modbus command to
transmit inside the Modbus packet will be as follows.
Slave address Function Code Byte Count Data
DEC 01 3 8 32.75 275.69
HEX 01 03 08 00 00 42 03 D8 52 43 89
In the above example the (a NON-Enron/Daniel supporting) Slave's Modbus
command that will be transmitted inside the Modbus packet will be as follows.
Slave address Function Code Byte Count Data
DEC 01 3 4 32.75
HEX 01 03 04 00 00 42 03