Communication Protocols
Copyright IXXAT Automation GmbH
102
IEM Manual, 1.5
5.2.3.2 Configuration assembly
Configuration assemblies share partly the behavior of both, host located varia-
bles and variables in the local object model.
Variables representing configuration assemblies are located at host and must
be marked with attributes
COM_k_ATTR_WRITE
,
COM_k_ATTR_HOST
in dw_attributes
and
COM_k_EIP_CONFIGURATION
in the s_eip.w_info field. If the IEM receives a
valid ForwardOpen request including configuration assembly data, the data is
forwarded to the associated host variable.
Changes of the configuration assembly data (by writing the specific instance
attribute of the assembly object) will be forwarded to the host by means of a
COM_k_FORWARD indication. The host may verify the changes and return an
error code if applicable.
For consistency reasons the host may preset the configuration data stored at
the module by means of an
APP_k_EIP_SET_ASSEMBLY_DATA
service request. This
request will be transmitted by calling EMI_srvreqSend(). Presetting the data
during startup would allow any remote device to request for the current appli-
cation configura-tion data.
5.2.3.3 Signal access
In some situations it may be useful for the host not only to control the error re-
sponses of existent attributes, but also to control error responses of non-
existent ones. A possible use case could be a host controlled object with a
flexible number of instances. Depending on the current accessibility of an in-
stance the error response of a generally unsupported attribute could be 0x14
(Attribute not supported) or 0x05 (Path destination unknown).
Generally, the EtherNet/IP stack of the IEM silently rejects requests to attrib-
utes not created during initialization. This behavior can be overwritten by the
additional variable attribute
COM_k_SIGNAL_ALL_ACCESSES
(see section 2.3.4 for
other variable attributes).
This attribute must be assigned to the s_eip.w_info field of the first attribute
created for a specific class. The attribute will affect the behavior of the com-
plete class, that is, requests to all instances and attributes (existent or non-
existent) of the complete object will be routed to the host. The host has then to
decide which error codes are to be returned in the responses.
5.2.4 Services
5.2.4.1 Ethernet/IP Services
Created variables can be accessed by means of two EIP services:
Get_Attribute_Single and Set_Attribute_Single (see [EIP1]). Other EIP ser-
vices for variables are not supported. Any received reset service request di-
rected to the local identity object will be signaled to the host application. The