Table of Contents
Advertisement
FS-8704-14 EtherNet/IP Manual
Appendix A.6.2.
The PLC Program
The PLC program example below shows the minimum steps necessary to program communications with the
FieldServer. Depending on the real intended application, additional steps may be necessary for completeness.
When the FieldServer is polling the PLC, all that is needed is to configure the tags being accessed:
Note that providing dedicated (long), flat structured (not UDT) tags for communicatons interface to the FieldServer
is preferable to polling single length tags in the PLC as it allows for much more efficient communications and
reduces complexity when mapping data in the FieldServer. It is better to think of these tags as a "I/O Buffer"
Interface that the real tags in the PLC get mapped to.
Appendix A.7. Read/write structures and value of EIP_Structure_Handle :
Some devices require that a specific value be used for the EIP_Structure _Handle field while writing the structure
to them. This value may be specified in the vendor documentation. If any non-zero integer is used in a Read Map
Descriptor for EIP_Structure_Handle, the value will be updated internally. The Map Descriptor can then be
browsed to obtain this value. Other devices do not validate this field when the structure is written by the third-
party device. A summary of the procedures to obtain this value is presented below:
FieldServer as a Client:
Read:
Use a value of 1, the driver will automatically update the field when a response is received from the
device. The Map Descriptor can then be browsed to obtain the value if required.
Write:
Use the value supplied by the vendor OR
Use the value obtained in the Read Map Descriptor above OR
Use any non-zero value if the other device doesn't validate it.
FieldServer as a Server:
Read:
Use the value supplied by the vendor OR
Use the value obtained in the Read Map Descriptor above OR
Use any value if the other device doesn't validate it.
Write:
Not required – use any non-zero value if the parameter is specified.
FieldServer Technologies 1991 Tarob Court Milpitas, California 95035 USA Web: www.fieldserver.com
Tel: (408) 262 2299 Fax: (408) 262 2269 Toll Free: (888) 509 1970 email: support@fieldserver.com
Tag Length must be equal to or greater than the
number of points being written/read
Page 22 of 30
Avoid Using UDT
Types. The Data will
be read but the exact
placement of the data
in the Tags and Arrays
will be hard to
determine
Advertisement
Table of Contents
