Setting Up an Aperiodic (Explicit) Server

The XEM CPU supports aperiodic (Explicit) server functionality on the EtherNet/IP network.

  • The Explicit server will automatically activate when an explicit client tries to access a variable selected for EIP usage.

  • Implicit Adapter (Server) setup must be done in the P2P EIP Channel and EIP Block. See Section 6 for setting this up.

The Explicit Server uses the EIP block indexes configured in the P2P EIP Block.

The index and channel must be in Implicit Server Operation mode for Explicit clients to access data.

Parameter Type Input Data Output Data
Service ID Get Attribute Single: 14 (0x0E) Set Attribute Single: 16 (0x10)
Class ID 4 4
Attribute ID 3 3
Instance ID Input Data Instance Information Output Data Instance Information
Size Input Data Instance Information Output Data Instance Information

Explicit Clients will need instance information for get single attribute commands.

  • The Instance number depends on the Index of the Data setup in the P2P EIP Block.

  • Index 0 will be Instance 100 and index 31 will be Instance 131. Instance value is 100 + Index number.

  • The Instance data size needs to be calculated from the value in the Data count column and the size of the data type of the Local tag.

Explicit Clients will need instance information for set single attribute commands.

  • The Instance number depends on the Index of the Data setup in the P2P EIP Block.

  • Index 0 will be Instance 150 and index 31 will be Instance 181. Instance value is 150 + Index number.

  • The Instance data size needs to be calculated from the value in the Data count column and the size of the data type of the Local tag.

The P2P EIP block data count column shows the number of elements in the local tag.

  • The data size for EtherNet/IP connections will need to be in BYTES for most cases.

  • This example will work for both Input and Output Instances.

  • This example will show the calculation of data size for Instance 150 and 153.

Instance 150 has a data count of 2 and the data type is USINT. USINT uses 1 byte of data. Data size for Instance 150 is 2 (Data Count) * 1 (USINT is 1 Byte) = 2 BYTES.

Instance 153 has a data count of 1 and the data type is REAL. REAL uses 4 bytes of data. Data size for Instance 153 is 1 (Data Count) * 4 (REAL is 4 Bytes) = 4 BYTES.

 

 

 

LP200-8