Error Responses; Command Message Format; Normal Response Message Format; Exception Response Message Format - Panametrics PanaFlow MV80 User Manual

4.2.6.10

Error Responses

If an error is detected in the message received by the unit, the function code in the response is the received function
code with the most significant bit set, and the data field will contain the exception code byte (see Table 12 below).
Exception Code
01
02
03
If the first byte of a message is not equal to the unit's Modbus address or if the unit detects a parity error in any
character in the received message (with even or odd parity enabled) or if the message CRC is incorrect, the unit will
not respond.
4.2.6.11

Command Message Format

The start address is equal to the desired first register number minus one. The addresses derived from the start
address and the number of registers must all be mapped to valid defined registers, or an invalid data address
exception will occur.
Device Address
8 bits, 1...247
4.2.6.12

Normal Response Message Format

Device Address
8 bits, 1...247
4.2.6.13

Exception Response Message Format

Device Address
8 bits, 1...247
PanaFlow™ MV80, MV82 & MV84 User's Manual
Table 12: Exception Codes
Invalid function code - function code not supported by device.
Invalid data address - address defined by the start address and
number of registers is out of range.
Invalid data value - number of registers = 0 or >125,
or incorrect data with the Write Single Coil command.
Table 13: Address Register Mapping
Function Code
8 bits
Table 14: Normal Response Message Format
Function Code Byte Count = 2 x N
8 bits
Table 15: Exception Response Message Format
Function Code + 0x80
8 bits
Description
Start Address N = No. of Registers
16 bits, 0...9998
8 bits (N) 16-bit registers
Exception Code
8 bits
Chapter 4. Serial Communications
CRC
16 bits, 1...125 16 bits
Data CRC
16 bits
CRC
16 bits
113