Reading Values - GE Multilin MIB Instruction Manual

A.1 READING VALUES
A.1READING VALUES
®
The ModBus function used is number 3 (READ HOLDING REGISTERS). The information retrieved from the relay is in
Intel format (little endian), that is to say, ordered from lower to higher weight (first the least significant byte, then the next
least significant byte and so on until the most significant one, that will go last). The message request command is
generated as follows:
Request:
A
Reply:
Example:
Reading 75 registers (150 bytes) beginning from address 04FEH (1278)
Request:
ADDRESS
01H
Reply
ADDRESS
01H
A-2
FIELD
Relay address
Function
Beginning address
Number of registers
CRC
FIELD
Relay address
Function
No. of bytes
Value of the registers
CRC
FUNCTION
03H
FUNCTION BYTES
03H 96H
MIB High Impedance Bus Differntial Relay
LENGTH
1 Byte
1 Byte (03h)
1 word (High Byte – Low Byte)
1 word (High Byte – Low Byte)
1 word
LENGTH
1 Byte
1 Byte (03h)
1 Byte
n data bytes /2 words (from lowest byte to
highest byte)
1 word
BEGINNING #REGS
04FEH 004BH
DATA0 ...
500DH
APPENDIX A
.
CRC
653DH
DATA74 CRC
0200H 84D5H
GEK-106426B