Device Address; Function Codes - JUMO LOGOSCREEN nt Interface Description

4 Modbus protocol description

4.5 Device address

4.6 Function codes

Function
summary
18
The device address for the paperless recorder can be set between 1 and 254
(decimal), see Chapter 3.4 Configuration of the serial interfaces, page 12.
A maximum of 31 paperless recorders can be addressed via the
RS485 interface.
Device address 0 is reserved as the Modbus broadcast address.
An instruction from the master for address 0 will be carried out by
all the slaves, but none of them will answer (because this would
lead to a data collision).
If only one recorder is connected to the PC or notebook, then it
can also be accessed through device address 255 (even if a
different address has been configured). The paperless recorder will
always respond to instructions for device address 255.
In the transmission protocol, the address is given in binary format
(hexadecimal).
The functions described below can be used to read out measurements and
other device and process data from the paperless recorder.
Function Function
number
0x01 or 0x02 read n bits
0x03 or 0x04 read n words
0x05 write one bit
0x06 write one word
0x10 write n words
If the recorder does not respond to one of these functions, or reacts
by generating an error code, then please refer to Chapter 4.9 Error
messages, page 25.
Restriction
max. 256 bits (16 bytes)
max. 127 words (254 bytes)
max. 1 bit
max. 1 word (2 bytes)
max. 127 words (254 bytes)