Configuring EtherNet/IP Explicit Messaging Using SEND_REQ
(Original Document)
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Configuring the Address Parameter
To configure the Address parameter, use the ADDR function to convert a character string to an address, as follows:
ADDR(‘{network.station}rack.slot.channel’)
NOTE:
  • The Xway address elements {network.station.} are required only when bridging through another PLC station.
  • The channel parameter is set to 0.
Configuring the Data_to_Send Parameter
The Data_to_Send parameter varies in size. It consists of contiguous registers that include—in sequence—both the message type and the CIP request:
Offset (words)
Length (bytes)
Data Type
Description
0
2 bytes
INT
Message type:
  • 0 = unconnected message
  • 1 = connected message
1
4 bytes
Bytes
Bytes 4 and 3 of the IP address1:
  • High byte = byte 4 of the IP address (MSB)
  • Low byte = byte 3 of the IP address
Bytes
Bytes 2 and 1 of the IP address1:
  • High byte = byte 2 of the IP address (MSB)
  • Low byte = byte 1 of the IP address
3
Management_Param[3] (size of Data_to_Send) minus 6
Bytes
The CIP request2. 
1
For example, the IP address 192.168.1.6 is handled as follows: byte 4 = 192, byte 3 = 168, byte 2 = 1, byte 1 = 6. 
2
Structure the CIP request in little endian order.
Contents of the Received_Data Parameter
The Received_Data parameter contains only the CIP response. The length of the CIP response varies, and is reported by Management_Param[3] after the response is received. The format of the CIP response is described, below:
Offset (words)
Length (bytes)
Data Type
Description
0
2
Byte
  • High byte (MSB): reserved
  • Low byte (LSB): reply service
1
2
Byte
2
length of additional status
Byte array
Additional Status1
...
Management_Param[3] (size of Received_Data) minus 4, and minus the additional status length
Byte array
Response data
1. Refer to The CIP Networks Library, Volume 1, Common Industrial Protocol at section 3-5.6 Connection Manager Object Instance Error Codes.
NOTE: The response is structured in little endian order.