Pepperl+Fuchs VBG-ENXK20-DMD-EV - Ethernet TCP;IP Functions; Function 3 (3 Hex): Read Multiple Registers; Function 16 (10 Hex): Write Multiple Registers

26.9.2013
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 000000000006090300040001
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
BD1
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