Rockwell Automation 8520-9API 9/Series OCI API Developer's Guide - Manual (Page 15)

1–6 Open Control Interface (OCI) Overview
Publication 8520-6.6 - August 1999
Status of Commands and POKE Data Items
When a data item read is successful no return code is sent to the
OCI, only the requested data is sent. When a data item or command
write is requested, the control will send a return code indicating that
the request was successful or failed. API data item POKE request
status is returned to the OCI in the reserved data item
“WRITE_ERROR_CODE”. Command status is returned to the OCI
in the reserved data item COMMAND_ERROR.
See page C–1 for details on error handling.
Errors on Automatic Items
When your OCI application requests a data item as automatic, the
OCI data server requests that item be added to the watchlist on the
specified CNC (refer to the data item chapter in this manual for
details on the CNC watchlist). If this data item is invalid for some
reason (e.g. bad syntax, not a valid item, watchlist full) the control
will return an error to the OCI data server indicating the error and the
item was not added to the watchlist. These errors are returned as text
to the requesting DDE object (e.g., Server Error [29]). See Chapter
3 for details on how we use a CNC based watchlist for automatic
items.
Errors on Manual Items
When your OCI application requests a data item as manual, the OCI
data server requests a value for that item from the specified CNC. If
the data item is invalid the control will return an error to the OCI
data server indicating the error condition. These errors are returned
as text to the requesting DDE object (e.g. Server Error [29]).
RSLinx OEM is installed on your windows workstation as an
integral part of a complete OCI system. This Rockwell Software
utility provides the OCI DDE data server access to the 9/Series CNC
through an ethernet connection.
A copy of RSLinx OEM comes with each OCI system you purchase
from Allen–Bradley. RSLinx is not included with the development
tool. For each OCI station that you create or ship you must purchase
an additional RSLinx license for that station. Contact your Rockwell
Automation sales representative for additional RSLinx licenses.
RSLinx OEM