Beckhoff BC8050 User Manual

RS232 - Interface
BC8050 und BC8150 73Version: 3.0.0
6.1.1.5.7 Function 23: Writing and reading of several analog value outputs or inputs
A number of analog outputs can be written and a number of analog inputs read with one telegram using
function 23. In this example the first 2 analog output words are written, and the first two analog inputs are
read. The analog outputs start at offset 0x0800, while the inputs start at offset 0x0000. Here the offset
always describes a word. Offset 0x0003 writes to the fourth word in the output process image. The length
indicates the number of words, and the Byte count is formed from the combination of all the bytes that are to
be written.
Example: 4 words - correspond to a byte count of 8
The data bytes contain the values for the analog outputs. In this example, two words are to be written. The
first word is to receive the value 0x3FFF, and the second word is to receive the value 0x7FFF.
Query
Byte Name Modbus RTU Modbus ASCII
Start - frame - - ":" 0x3A
Address 11 0x0B "0B" 0x30, 0x42
Function code 23 0x17 "17" 0x31, 0x17
Read start address high 0 0x00 "00" 0x30, 0x30
Read start address low 0 0x00 "00" 0x30, 0x30
Read length high 0 0x00 "00" 0x30, 0x30
Read length low 2 0x02 "02" 0x30, 0x32
Write start address high 8 0x08 "08" 0x30, 0x38
Write start address low 0 0x00 "00" 0x30, 0x30
Write length high 0 0x00 "00" 0x30, 0x30
Write length low 2 0x02 "02" 0x30, 0x32
Byte Count 4 0x04 "04" 0x30, 0x34
Data 1 high 63 0x3F "3F" 0x33, 0x46
Data 1 low 255 0xFF "FF" 0x46, 0x46
Data 2 high 127 0x7F "7F" 0x37, 0x46
Data 2 low 255 0xFF "FF" 0x46, 0x46
Error check, LRC/CRC 0x76, 0xD3 "12" 0x31, 0x32
End - frame t1-t2-t3 CRLF 0x0D, 0x0A
Response
The Bus Coupler/Fieldbus Box responds with the start address and the length of the transferred bytes in the
byte count. The data information follows. In this example the first word contains 0x0038 (hex) while the
second word contains 0x3F0B.
Byte Name Modbus RTU Modbus ASCII
Start - frame - - ":" 0x3A
Address 11 0x0B "0B" 0x30, 0x42
Function code 23 0x17 "17" 0x31, 0x17
Byte Count 4 0x04 "04" 0x30, 0x34
Data 1 high 0 0x00 "00" 0x30, 0x30
Data 1 low 56 0x38 "38" 0x33, 0x38
Data 2 high 63 0x3F "3F" 0x33, 0x46
Data 2 low 11 0x0B "0B" 0x30, 0x42
Error check, LRC/CRC 0xF8, 0xA7 "E3" 0x45, 0x33
End - frame t1-t2-t3 CRLF 0x0D, 0x0A

Beckhoff BC8050 Specifications

General

Brand	Beckhoff
Model	BC8050
Category	Controller
Language	English