KROHNE MFC 010 C Converter - Manual (Page 28)

26
MFC010 Interface Manual
6.4 04 (04
16
): Read Input Registers
This function permits the user to read the value of a number of consecutive Input registers. (See Section
7.5 on page 493 for details of the individual registers). The format of the Master request telegram for this
function should be as follows.
Request
Character
Field For Example
1 Slave Address 01
16
Request to Slave ID 1
2 Function 04
16
“Read Input Registers”
3 Start Address Hi 0B
16
Start Address = 3001
4 Start Address Lo B8
16
5 No of Points Hi 00
16
No. of Points = 2
( Input Registers 3001 – 3002 ) 6 No of Point Lo 02
16
7 CRC Lo F3
16
CRC Checksum
8 CRC Hi CA
16
The MFC010 will respond to such a request with a telegram formatted as follows.
Response
Character
Field For Example
1 Slave Address 01
16
Response from Slave ID 1
2 Function 04
16
“Read Input Registers”
3 Data Bytes in Response 04
16
4 bytes ( 2 x 2 Byte Registers )
4 Data Byte 1 94
16
Register 3001 / 3002 = 75.29
5 Data Byte 2 7B
16
6 Data Byte 3 42
16
7 Data Byte 4 96
16
8 CRC Lo 17
16
CRC Checksum
9 CRC Hi 63
16
In t he ex ample abov e t he I nput r egister r equested c ontains a f loating poi nt num ber and needs to be
accessed as a pai r of r egisters ( 3001/3002). T he r esulting 4 by tes i n t he dat a r esponse c an t hen be
decoded into a floating-point number (See Section 5.3 on page 20 and Appendix C on page 93 for further
details on encoding and decoding floating point numbers).