Laurel Electronics Modbus Protocol For Series 2 Laureate Digital Panel Meters, Counters, Timers & DIN-Rail Transmitters - Manual (Page 14)

- 14 -
8. SUPPORTED EXCEPTION RESPONSE CODES
Code Name Error Description
01 Illegal Function Illegal Function Code for this Slave. Only hex Function
Codes 03, 04, 05, 08, 10 (dec 16) are allowed.
02 Illegal Data Address Illegal Register Address for this Slave and/or Register
Length.
03 Illegal Data Value Illegal data value or data length for the Modbus protocol.
04 Slave Device Failure Slave device failure (eg. Device set for external gate).
9. MESSAGE FORMATTING
MA = Meter Address DD = Data (Hex) CL = CRC Lo Byte
FC = Function Code WW = Data (On/Off) CH = CRC Hi Byte
RA = Register Address SF = Sub-Function CR = Carriage Return
NR = Number of Registers EC = Error Code LF = Line Feed
NB = Number of bytes LRC = ASCII Checksum
Modbus RTU Format
Byte Number
FC Action
> 3.5
Char
1 2 3 4 5 6 7 8 9 10 11
03
03 Request
Response NoTx
NoTx MA
MA FC
FC RA
NB RA
DD*
NR
DD*
NR
CL
CL
CH
CH
04
04 Request
Response NoTx
NoTx MA
MA FC
FC RA
NB RA
DD*
NR
DD*
NR
CL
CL
CH
CH
05
05 Request
Response NoTx
NoTx MA
MA FC
FC RA
RA RA
RA WW
WW WW
WW CL
CL CH
CH
08
08 Request
Response NoTx
NoTx MA
MA FC
FC SF
SF SF
SF WW
DD
WW
DD
CL
CL CH
CH
10
10 Request
Response NoTx
NoTx MA
MA FC
FC RA
RA RA
RA NR
NR NR
NR NB
CL
DD*
CH
DD* CL CH
Exception
Response
NoTx MA FC
+80
EC CL CH
DD* = (DD DD) times NR (Number of Registers)
Modbus ASCII Format
Except for the colon, CR and LF, each column is 2 hex character bytes.
DD* = (DD DD) times NR (Number of Registers)