FG_F6_MODBUS_EN_01 / 2020-06-17
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Direct access
In Direct access, the master can only access to parameters one by one.
This is an example on the reading of the end of cycle bit in the status:
Master
Slave
—
Make a
Read N*words
request of 1 word at the
2204h
address.
On network:
01
03
22
04
00
01
CF
B3
01
Slave address
03
Function number (Read N*words)
22 04
D.A. address
00 01
Number of words to read
CF B3
CRC
—
Answer to the request:
On network:
01
03
02
21
80
A1
B4
01
Slave address
03
Function number (Write N*words)
02
Number of read bytes
21 80
Word 1: read 8021h
(cycle end = 8021 & 0020 = 1)
A1 B4
CRC