IC-Module for EtherNet/IP
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Reading 2 bytes (Word)
This access type is used if just 1 register is to be read from a
memory register of the module by the Master. The Master first sends
a data block with a fixed length of 5 bytes, which have the following
content:
Transmission block with fixed length
Command
code
(1 byte)
Address area
(2 bytes)
Not
used
(2 bytes)
Description
0x10
0x0000-0xFFFF
0xXXXX
READ_WORD
0x00
0xXXXX
0xXXXX
NO_OPERATION*
* This command allows the master to request the status of a read request without an additional read or write request
having to be executed.
Theoretically, you could use all memory register addresses between
0 and 0xFFFF. In practice, only the registers implemented in the
firmware can be read. You can find out which registers these are in
Chapter “Memory Registers [
}
13]”.
During transmission of the first data block, the module sends the
status of the previous data transmission. The module first returns the
data to be read when sending the next data block. If, however, no
further write or read operation should follow the read access, then
the Master must send another data block with the command code 0
("NO_OPERATION") for retrieving the data to be read, in which the
module returns the status for the last access operation.
The response from the module is structured as follows for all read
access operations:
Transmission block with fixed length
Status code
(1 byte)
Error code
(2 bytes)
Data area
(2 byte)
Description
0x00
0xXXXX
0xXXXX
NO_PREVIOUS_OPERATION
0x04
0x0000
0x0000-0xFFFF
READ_SUCCESS
0x08
ERROR_CODE
1
0xXXXX
READ_FAILURE
1 See Table "ErrorCode"
Components
