J-Bus/ModBus Protocol
PR5230 Instrument Manual
EN-150
Sartorius
6.4.7
Function 16: Writing n Successive Words
Command Device
address
Function
number
Address of
1st word
Number of
words
Number of
bytes
Value of
words
1 byte
1 byte
2 bytes
2 bytes
1 byte
n bytes
Range 0...127
16
0...63
1...64
2...128
MSB
LSB
MSB
- - - - - - MSB
LSB
1
st
word
last word
Reply Device
address
Function
number
Address of 1st
word
Number of
words
1 byte
1 byte
2 bytes
2 bytes
If the address is out of the permissible range (0...63), an error message is sent as a reply (the address plus the
number of bytes must not exceed 64).
Example of function 16 for writing the limit_1 switch-on point using value 893 with ModBus-RTU:
Command
1 16 0 48 0 2 4 0 0 3 125
CRC
CRC
Reply
1 16 0 48 0 2 CRC
CRC
The individual bytes are shown.
6.5
Error Messages
If a command was transmitted correctly, but cannot be executed because e.g. the address is too high, an error
message is sent as a reply to the command.
The error message has the following format:
Device address
Function 128
Error number
CRC 16
1 byte
1 byte
1 byte
2 bytes
The 2nd byte contains the received function number; the most significant bit is set additionally.
Meaning of the error number:
1
The function number is unknown
2
The address is out of the permissible range
3
The data format is faulty (e.g. more data than specified in the number were written)
Example of an error message, which was generated by an invalid function number with ModBus-RTU.
Command
1 9 0 0 0 0 CRC
CRC
Reply
1 137
1 CRC
CRC
The individual bytes are shown.
