Rockwell Automation 1757-PROCESSLINX ProcessLinx OPC Server to Server Software User Manual - Manual (Page 45)

1 Publication 1757-UM002B-EN-P - January 2003
Chapter
4
ProcessLinx Runtime Operation
Each Pipe created in ProcessLinx provides a conduit to pass information
between OPC Servers. An OPC Server cannot communicate directly to
another OPC Server. Each OPC Server expects responses that are normally
received from an OPC Client. ProcessLinx uses OPC Client responses to
receive data from one OPC Server and transmit it to another OPC Server.
When runtime mode is started, the Groups defined in each ProcessLinx Pipe
are created in the respective OPC Servers. Then, all OPC Items defined by the
Groups’ TagMaps are added. Data is transferred from OPC Server to OPC
Server based on the Group’s settings. The OPC Groups and Items in disabled
Pipes are not connected to in runtime. The Enable checkbox is found in the
Pipe Properties Dialog.
Monitoring Values In runtime, monitor OPC Items by selecting View
⇒
Monitor from the main
menu. Current values appear under the Value1 and Value2 columns in the tag
view pane. If the Server or Group is not connected (or is disabled), the values
are displayed as “Uncertain” or “Bad”. Monitored values are refreshed every
100 milliseconds. Select another Group to view its TagMap values.
Reading OPC Values ProcessLinx allows any OPC Item to be read during runtime. Select and right
mouse click on the desired TagMap’s OPCItem1 column in Select Read
⇒
OPCItem1 or OPCItem2 from the corresponding pop-up menu.
IMPORTANT
Groups that have “write only” data flow may not present
the latest available data from the OPC Server. The
displayed value is the last value written to the OPC Server.
No OPC Server “reads” are executed for these Group
types.
TIP
If the tagmap displays with a !, then one or both of the
OPC Items defined within that tagmap are invalid. This
means that the OPC Item does not exist within the Server
or is mis-configured in the ProcessLinx with an incorrect
item name.