4 functions, Function 1 or 2: reading n bits, Functions – Rice Lake PR5230 Fieldbus Transmitter User Manual
Page 170: J-bus/modbus protocol, Pr 5230 instrument manual
J-Bus/ModBus Protocol
PR 5230 Instrument Manual
EN-170
Sartorius
6.4
Functions
Function 1 or 2: Reading n Bits
Command
Device
address
Function
number
Address of
1st bit
Number of
bits
1 byte
1 byte
2 bytes
2 bytes
Range
1...127
1, 2
0, 8 , 16...
8, 16, 24...
The bit address must always be the 1st bit of a byte. The number of bits to be read may not be smaller than 8
and must be a multiple of 8.
Reply
Device
address
Function
number
Number of
read bytes
Value of 1st
byte
Value of 2nd
byte
..
Value of last
byte
1 byte
1 byte
1 byte
1 byte
1 byte
1 byte
8. ...1. bit
last bit
If the address of a bit to be read is out of the permissible range (0...127), an error message is sent as a reply
(the address plus the number of bits must not exceed 128).
Example of function 1 for reading the status bits of the scale (8 bits start at bit 32) with ModBus-RTU.
Command
1
1
0
32
0
8
CRC
CRC
Reply
1
1
1
X
CRC
CRC
Example with ModBus-TCP:
Command
47
11
0
0
0
6
0
1
0
32
0
8
Reply
47
11
0
0
0
4
0
1
1
X
The individual bytes are shown.
The read byte X
Bit 0 = bit 32 of SPM = ADC error
is interpreted as follows:
Bit 1 = bit 33 of SPM = above Max (maximum capacity)
:
Bit 6 = bit 38 of SPM = weight is stable
Bit 7 = bit 39 of SPM = weight is below zero or above Max