Hach Anatel PAT700 User Manual page 152

Modbus Protocol
Value (Hex)
1.0 (as in memory)
0x000000000000F03F
1.0 (after swapping)
0x0000000000003FF0
1st Register
Value (String) 1st
'HachUltra' 0x48
Page 150
Double
A Double float value is 64-bits within the Anatel PAT700 TOC Analyzer. FC3 reads 16-bit
items at a time; therefore, four registers are required to read each Double float data item.
Note: The Modbus/TCP protocol follows Little Endian - byte swap format while transmitting Double
float data i.e. LSB byte should come first in a Register. The swapped data on Client side has to be
converted back to original format to read the correct value.
Example (Double Float): 1.0
1st Register
1st 2nd
0x00 0x00
1st Register
2nd 1st
0x00 0x00
Strings
A string is a group of 8-bit data items having a fixed length. The first character of a string
is transmitted first, followed by the remaining characters. FC3 reads 16-bit items at a
time; therefore, a single register contains two characters of the string. To simply string
storage/transfer, each string should be of an even-byte length.
Example (String): HachUltra
2nd Register
2nd 1st
0x61 0x63
IP Address
An "IP Address" is transmitted similar to a 32-bit Word with the MOST significant byte
first, then the next MOST significant, until all the bytes are transmitted. FC3 reads 16-bit
items at a time; therefore, two registers are required to read each IP Address data item.
Example (Decimal): 192.168.0.1
Value (Hex)
0xC0A80001
2nd Register
1st 2nd 1st
0x00 0x00 0x00
2nd Register
2nd 1st 2nd
0x00 0x00 0x00
3rd Register
2nd 1st 2nd
0x68 0x55 0x6C
1st Register
1st 2nd
0xC0 0xA8
3rd Register 4th Register
2nd 1st
0x00 0xF0
3rd Register 4th Register
1st 2nd
0x00 0x3F
4th Register 5th Register
1st 2nd 1st
0x74 0x72 0x61
2nd Register
1st
0x00
2nd
0x3F
1st
0xF0
2nd
0x00
2nd
0x01