ACS 601.86861.00 Operation And Instruction Manual page 46

MODBUS Function 03 Request. The format for a function 03 request is shown below.
Device
Address
1 byte
MODBUS Function 03 Request Example. Suppose you want to Read Delivery
Temperature in Float 32 Bit IEEE Format, which has registers address of "4002" and if the
controller ID is "01".
Device
Address
$01
Function 03 Normal Reply. The controller reply will consist of the following data:
01= MODBUS unit ID
03= MODBUS command: read holding registers
0F = high byte of first register to read
A2 = low byte of first register to read
00 = high byte of number registers to read
02 = low byte of number of registers to read
66 = low byte of CRC of command packet
FD = high byte of CRC of command packet
Following is an example of normal reply response showing Process Temperature = 37.6° C
Device
Address
$01
M2C Advanced
Function Code Register Address
03
1 byte MSB
containing $03
Function Code Register Address
03
$03 $0F
0FA2 = 4002 decim al
2 = 16-bit registers are read in a single command, to get all of a 32-bit floating
point register
Function Number Bytes
Code 03 of Data
$03 $04
682.98769.00
Number Of Words
To Read
LSB MSB
Number Of
Words To Read
$A2 $00
IEEE32 BitFloat Data Field See
Modbus Spec.
$C0 $93 $42
• 8/24/18
CRC
LSB MSB LSB
CRC
$02 $66 $FD
CRC
$16 $87 $70
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