Read N Bits; Read N Words - JUMO LOGOSCREEN nt Interface Description

4.6.1 Read n bits

Data request
Response
Example

4.6.2 Read n words

Data request
Response
Example
This function reads n bits, starting from a defined address.
Slave Function
address 0x01 or 0x02
1 byte 1 byte
Slave Function
address 0x01 or 0x02
1 byte 1 byte
The response is always made in complete 8-bit bytes.
The byte values that are not required are filled with the value 0.
Read one bit, starting at address 0x0340 (word address 0x0034).
For addresses, see Chapter 7.1 Modbus addresses for important device and
process data, page 43.
Data request:
01 02 0340
Response:
01 02 01
This function reads n words, starting from a defined address.
Slave Function
address 0x03 or 0x04
1 byte 1 byte
Slave Function
address 0x03 or 0x04
1 byte 1 byte
Read the first 3 analog inputs (i.e. the first 6 words starting at Modbus address
0x1257).
For the addresses of the analog inputs, see Chapter 7.1 Modbus addresses
for important device and process data, page 43.
4 Modbus protocol description
Address
first bit
2 bytes
Number
of bits read
1 byte
0001 B85A
01 6048
bit value
Address
of first word
2 byte
Number
of bytes
read
1 byte
Number Checksum
of bits CRC16
2 bytes 2 bytes
bit Checksum
value(s) CRC16
x byte(s) 2 bytes
Number Checksum
of words CRC16
2 bytes 2 bytes
Word Checksum
value(s) CRC16
x byte(s) 2 bytes
19