26
.9.20
1
3
80
AS-i 3.0 EtherNet/IP+Modbus TCP Gateway
Operation via Ethernet IP (Modbus/TCP)
Example transaction:
Read 1 register at offset 4 from UI 9. Return value is 5
12.2
Ethernet TCP/IP functions
In the following chapter are shown the support functions. Please note, that only
the related bytes are shown (bytes 0 - 3 are let away, because the values are 0).
12.2.1
Function 3 (3hex): "Read multiple registers"
This function allows to read the value of read/write-registers.
12.2.2
Function 16 (10hex): "Write multiple registers"
This function allows the setting of several read/write-registers:
Information!
Checksum fields are not needed, because the TCP/IP and link layer (eg. Ethernet)
instad are used to verfiy accurate delivery of the packet.
request
00
00
00
00
00
06
09
03
00
04
00
01
response
00
00
00
00
00
05
09
03
02
00
05
request:
3
R1
high
R2
low
N1
high
N2
low
response:
3
B
D1
high
D1
low
… Dn
high
Dn
low
R1/R2: reference number (high byte / low byte)
N1/N2: word count (range 1 - 125) (high byte / low byte)
response:
B: byte count of response (b = 2 x word count)
D: register values
request:
10
R1
high
R2
low
N1
high
N2
low
B
D1
high
D1
low
...
Dn
high
Dn
low
response:
10
R1
high
R2
low
N1
high
N2
low
R1/R2: reference number (2 byte hex-value of register
e.g. 8192 = 0x2000)
N1/N2: Word count (1 - 100) (2 byte)
B: byte count of response (B = 2 x word count / 1 byte)
(redundant information to word count but necessary).
D1 … Dn: register values
