Overview
:

OPC - OLE
for Process Control - was created as a vendor-independent
standard aimed at the definition of data exchange between
Microsoft Windows application as well as applications
and vendor specific hardware in the realm of automation
and industry. Many industrial hardware vendors provide OPC servers
for their products like data acquisition boards, PLCs,
fieldbus controllers, etc.
OPC is maintained
by an independent association - the OPC Foundation -.
OPC defines a series of standard specifications. This
MxM acts as a client for both "OPC Data Access"
server and/or "OPC Alarms & Events" server.
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Installation
(MXM) :
No
installation is required if the OPC Server runs on the
same machine as Manager and this section can be skipped.
If
the OPC Server runs on another machine the following steps
must be done:
1.
Install OPC Core Components
Unzip
the attached ">
OPC Core Components Redistributable 3.00.102.zip"
file in a temporary location and and execute "Setup.exe".
2.
Setup COM/DCOM
This
MxM uses OPC to communicate with OPC servers. OPC itself
is based upon the Microsoft COM/DCOM technology. Thus
the MxM requires that COM/DCOM is properly configured
on both the server and the client machines in order to
work correctly, in particular DCOM security settings and
firewall settings must be carefully set when the MxM (which
acts as an OPC Client) must communicate with an OPC Server
on a remote machine.
Please
refer to ">
Using OPC via DCOM" document for detailed instructions.
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Creation
(Device) :
Device Creation Window :

IP or Hostname:
IP Address or Hostname
of the PC which hosts the OPC server.
The local machine is used if this entry is left blank.
Browse OPC Server:
This button allows browsing the OPC Servers installed
on the specified machine and populates the "Select
Server" combo box with the names of the found OPC
servers.
Select Server:
This combo box lists all of the OPC Servers installed
on the specified machine (after the "Browse OPC Server"
button has been pressed).
Server GUID:
This edit box shows the GUID (Global Unique Identifier)
of the selected OPC server. This field is normally used
for information
purpose only and must not be modified.
However the GUID of the
OPC server can be specified
manually in special cases where the OPC server would not
be registered correctly in the target host Windows registry.
Enable
OPC Data Access:
When checked an OPC Data Access connection to the specified
OPC server will
be established when the device is started. Otherwise
OPC Data Access is not enabled.
Configure OPC Items and Monitoring:
Pressing this button opens a dialog box which displays
all of the OPC Data Access Items found on the specified
OPC server.
For each found OPC Data Access Item the user can specify:
- whether the selected items should be monitored by a
System Variable (by checking the item check box or choosing
"Set Monitor On/Set Monitor Off" menu item
or the popup menu)
- the type of the monitoring variable if the selected
items are monitored (a default variable type is computed
from information obtained from the OPC Server).
- whether
the selected items are "active" (that is processed
by the OPC Client). Note that an item must be "active"
for the "Read Item Value" and "Write
Item Value" commands to work.

The "Get OPC Item" button can be used to refresh
the list of OPC Data Access items.
Enable OPC Alarm & Event:
When checked an OPC Alarm & Event connection to the
specified OPC server will be established when the device
is started. Otherwise OPC Alram & Event is not enabled.
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Commands (List Of) :
Read
Item Value:
Write
Item Value:
Read
Next Event:
Description:
Reads the next event stored in the event queue and
stores event information in specified return parameters.
Parameters:
Date: [Type: Date] Date the event has occured
Time: [Type: Time] Time the event has occured
Message: [Type: String] Message of the
event
Source: [Type: String] Name of the source item
which has triggered the event
Ack Required: [Type: Integer] Whether an acknowledgement
is required for this event (0: No Ack required, 1:
Ack required).
Event
Type: [Type: Integer] Type of the event (0: Simple
Event, 1: Tracking Event, 2: Condition Event).
Condition: [Type: String] Name of the condition
which has triggered the event
SubCondition: [Type: String] Name of
the subcondition which has triggered the event
Severity: [Type: Integer] Severity of the event
(ranging from 1 to 1000, low to high)
Usage: This commands pulls out the least recently
received event from the event queue (if any) and decrements
the count of pending event.
Return parameters are optional, for example, there's
no need to specify a "Severity" return parameter
if if there's no use of this information in the Manager
project.
The type of return parameter is not mandatory and
the programmer can use the type of parameter which
best suits his needs. For example a user defined enum
variable can be used as a return parameter for "Event
Type".
This command works only if "OPC Alarm & Event"
is enabled.
Acknowledge
Event:
Description:
Sends an acknowledge to the OPC Server for the last
event retrieved by the "Read Next Event"
command.
Parameters:
Acknowledger ID: [Type: String] A user defined string which identifies the
acknowledger (for example, the name of the logged
user as defined in the Manager project)
Comment: [Type: String] A comment associated to the acknowledgement.
Usage: This command acknowledges the last
retrieved event only if the "Ack Required"
parameter of the event is true. Otherwise it does
nothing.
This command works only if "OPC Alarm & Event"
is enabled.
Area
Condition :
Source
Condition :
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Variables (List Of) :
Connection_Status:
Command_Status :
Type : Enum.
Description : Status of the last command.
Available Values :
"Idle": No command is in progress.
"Busy": The device is busy issueing a command.
"Error": An error has occured while the command is
executed.
"Wait for Answer": The device is waiting
for an answer from the OPC Server.
"Command Timeout": A timeout has been detected.
Error_Message :
Type : String.
Description : Detailed description of the last
error.
AlarmEvent_Status:
Type
: Enum.
Description : Current status of the Alarm and
Event connection.
Available Values :
"Unconnected" : The device is not connected to
the OPC Server.
"Connecting" : The device is connecting to the OPC
Server.
"Connected" : The device has been successfully connected
to the OPC Server.
"Unconnecting" : The device is disconnecting to the OPC Server..
"Message
Overflow" : Too many OPC Alarms & Events messages
have been received in the pending message queue.
AlarmEvent_PendingCount:
Type : Integer.
Description : Number of Alarm and Event messages
which were received and queued in the pending message
queue.
Usage: a task can be triggered when this variable changes
is greater than 0 in order to retrieve messages from
the pending message queue and display them. This variable
is decremented each time a message is retrieved by the
"Get Next Event" command.
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Support
(Difference with previous versions) :
V 1.0.1:
- Added: Support for Showmaster.
V 1.0.2:
V 1.0.3:
- Added: support for Siemens OPC Server in DCOM Mode.
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