LinkMaster OPC Bridging Software

Overview

LinkMaster provides the means of linking data between OPC Servers, thus acting as a universal bridge for OPC Systems. Additionally, LinkMaster is an OPC and DDE server allowing it to act as a bridge between legacy DDE systems and new OPC enabled applications.

Industrial Strength Reliability
A few of the industries that rely on LinkMaster include:
Aerospace, Automotive, Building Automation, Material Handling, Medical, Power Generation, Primary Metals, Pulp & Paper, Refining, Timber, Utilities

Programming Knowledge Optional
LinkMaster is a fast and robust Windows application that requires no programming knowledge, simply "Drag and Drop" to create your links. Built-in scaling, user-access manager, error tracking, and write optimization capabilities, provide total control of your data flow and application access.

Control Data Transfers with Link Groups
Link Groups are used to form collections of OPC items that will be moved between OPC servers at a specified rate. Using multiple Link Groups, LinkMaster allows you to control how fast data is transferred from one OPC server to another. By using Link Groups with different update rates you can tailor your data transfers to fit the needs of the application. While one item may need to be sent at high speed, other items in the application may need slower update rates. Link Groups gives you that control. The benefit is reduced network traffic and increased reliability

Diagrams

OPC Server to OPC Server Bridging
The most common scenario for LinkMaster is to link data between two (or more) OPC Servers. An example might be a customer using RSLinx for connectivity to Allen Bradley PLCs and Kepware's U-CON Protocol Server for connectivity to a checkweigher. In this example the customer wants to easily send scale data to the PLC.

OPC Server within Server bridging
This scenario is commonly used when a customer wants to route data between two PLCs connected to the same server. Using LinkMaster to define the tag data routing can be much easier than creating new ladder logic in your PLCs (especially for legacy systems). An example might be a customer using KEPServerEX to connect to an Allen Bradley ControlLogix PLC as well as a Yokogawa DX Data Recorder.

OPC Server Collector or Gateway
Another interesting application scenario for LinkMaster is to function as a single OPC server which serves data from multiple OPC servers. This approach demonstrates LinkMaster's capability of acting as both a client and server. An example might be when a customer has a single OPC connection available from an OPC client application but multiple OPC servers that they want to acquire data from.

OPC link between PLC and DCS
A powerful but simple link scenario for LinkMaster is to use it to share data between a PLC and a DCS. In this example, both device systems have an OPC server connected to them to make data available to OPC client applications but they do not have an easy way to share data with other servers. An example might be that a paper mill needs to send gauging system data to a PLC. Honeywell's Davinci server would communicate with the Measurex gauging system in the DCS. LinkMaster would pass data from the Davinci Server to Kepware's OPC server KEPServerEX and KEPServerEX would send the data to the Siemens S7 PLC.

Flow

Server to Server Linking

The most common scenario for LinkMaster is to link data between two or more OPC Servers.

Collector or Gateway

LinkMaster has the capability of acting as both an OPC Client and OPC Server.

Features

Built-in Redundancy
Fully featured data "bridging"
Supports both COM & DCOM
OPC1.0.a/2.0 compliant
Runs as Windows NT/2000 Service
"Drag & Drop" link creation.
Error Logging.
Supports direct scaling of link item data.
LinkMaster's link management system allows you to create a Link database structure that fits the nature of your application.
Includes a built in User Manager that allows complete control over what types of functionality each individual user can access.
Support for creating Custom Remote Machine references.
Includes a stand alone event monitoring application called the EventViewer.
OPC Data Access Version 1.0a
OPC Data Access Version 2.0
DDE Format CF_Text
DDE Format AdvancedDDE

Solutions

Solution Chronicles

Schmidt engineers decided to review Kepware's OPC server suite (KEPServerEX) as well as Kepware's OPC system bridging software package (LinkMaster). KEPServerEX would provide the Ethernet connection to the GE Fanuc PLC, and LinkMaster would bridge or "link" the OPC data between the Schmidt OPC server and KEPServerEX. During the development stage of this project, the fully functioning 2-hour demo packages of KEPServerEX and LinkMaster were downloaded from Kepware Technologies - free of charge!

LinkMaster a Success at Schmidt! SCHMIDT Technology Corp. a wholly owned subsidiary of SCHMIDT Technology - Germany, offers a comprehensive line of precision Manual, Air-Powered, and Hydro-Pneumatic presses for manufacturing industries in the United States, Mexico, and Canada. With its most recent introduction of (5) five ServoPress Models, certain challenges were presented to the SCHMIDT Technology control engineering staff in how to communicate electronic data between control systems.

The SCHMIDT Technology PRC4000 6-axis ServoPress controller is an "open source" logic and servo control unit that provides sequencing, calculating, process monitoring, SPC, and motion control, as well as a built-in HMI. This controller also contains an OPC server that is used as an interface to allow for real-time exchanging of data with OPC clients. By using an OPC interface, any word or Boolean information can be easily exchanged between the SCHMIDT controller and another PC-based control, HMI, or PLC. In a recent medical application, the PRC4000 ServoPress controller was required to provide force data to a GE Fanuc PLC that was functioning as a master controller on an assembly line. This application also required the involvement of providing status of force monitoring, sequence information, and real-time access to additional force and position data from two ServoPress modules.

Fast, Easy, and Reliable Connectivity It is important to note that, during this process, SCHMIDT engineers did not have a GE Fanuc PLC in-house to test the data transfer. However, they did have several Allen Bradley Micrologix PLCs on hand. Because KEPServerEX also provides connectivity to Allen Bradley PLCs, the SCHMIDT team was able to install the KEPServerEX OPC server suite and the LinkMaster application on the PRC4000 controller. They used Kepware's Allen Bradley DF1 connectivity to communicate directly to the PLC through a serial port. Next, LinkMaster was quickly configured to acquire the data to/from the SCHMIDT OPC server, and map the integer and Boolean data directly to available integers and bits within the AB PLC. Due to the reliability and ease of use of the in-house evaluation system, SCHMIDT engineers made the decision to use Kepware's solution at the customer site. Kepware's OPC server provides a single consistent interface to a variety of industrial protocols. This made the transition from the in-house AB to the on-site GE connectivity fast and easy. KEPServerEX with GE connectivity and the bridge application LinkMaster were installed on the PRC4000 controller allowing a successful and seamless exchange of data through the on-board Ethernet port.

This fast, easy, and reliable solution provided by LinkMaster prompted a final configuration featuring the use of LinkMaster to transfer data and status/control bits between three PRC4000 controllers and the GE Fanuc PLC.

More information about Schmidt Technology Corporation can be found by navigating to: www.schmidtpresses.com

Required

Required Software and Hardware

Supported Operating Systems

Windows NT
Windows 2000
Windows Server 2003
Windows XP

PC Hardware

Minimum

400 Mhz Pentium CPU
128 Megs of RAM
100 Megs of Free Hard Drive Space

Recommended

600 Mhz Pentium CPU
512 Megs of RAM
100 Megs of Free Hard Drive Space

Links

View LinkMaster Connectivity Guide (PDF)
LinkMaster Brochure (PDF)
OPC Overview
Product Revisions
Hardware Accessories
Related Software

Revisions

LinkMaster Updates and Latest Version No.

Build	Issue/Enhancement/Fix
V2.37.124.0 November 16, 2007	Enhancements: - Added "Redundancy" feature. This feature allows a pair of LinkMaster machines to operate in redundant pairs where one LinkMaster machine operates as the "Primary" node and the other in "Secondary" mode. When the "Primary" node fails, the "Secondary" node promotes itself and takes over the role of the primary. When the "Primary" node comes back up again, the "Secondary" node demotes itself and lets the "Primary" node perform the data transfer. - Increased name field length from 31 to 80 characters for link items and link groups. - Added ability to disable reads in inputs when link transfers is disabled. - Added ability to allow LinkMaster connections to itself on the local machine. - Added link description sub-item to our link item display. Fixed: - Fixed issue where LinkMaster produced an anomaly when the OPC servers it is bridging are on a remote machine and the network connection on the LinkMaster machine is reset (connect/disconnect) very frequently. - Fixed issue when adding a link item that contains a data type that is not supported by LinkMaster. The item would be removed twice, the second time potentially removing a valid item which would then break the link. - Fixed painting issue with the item value display not updating correctly if all items in the view went to bad quality at the same time and the value was passed in as the last known value.
V2.20.108 July 19, 2006	Fixed: - Fixed issue where we would set the link group status to bad if we receive an item update for an input prior to attempting to add the output.
V2.20.107 June 13, 2006	Enhancements: - Added project backup capabilities. This feature will always perform a backup of an existing project file prior to overwriting the file. This option can be turned on through the Tools\|Options\|General menu item. Fixed: - Fixed issue where we would send a write to an output on the first update of the input, regardless of whether or not the quality associated with the input was good. - Fixed issue with returning OPC array data to remote clients over DCOM when acting as an OPC server. - Fixed issue where we would send a bad quality write to an output if the addition of the output item(s) occurs after we originally receive the bad quality input update. - Fixed issue where we could send a write to an output if the input server returned a value with good quality, but also included a failure code to indicate the VQT could not be set appropriately. - Fixed issue where you could not close message boxes invoked from either the link group or link item property dialogs.
V2.10.102 October 18, 2005	Enhancements: - Added support to retry AddItem requests to underlying OPC servers that previously failed the AddItems request. These are retried at a user-specified interval under Tools\|Options\|Links. - Added support for user to control how the application window is displayed when started by a client or minimized to the task tray. These settings are located under Tools\|Options\|View. - Added ability to select whether or not the application should retry writes to outputs that return a write complete failure. By default we will retry writes as this has been the default behavior prior to this feature. - Added support for Boolean arrays. Fixed: - We no longer allow users to make modifications to a project during an import CSV operation. This should have been the case in earlier releases. This prevents painting issues caused by this condition. - Fixed issue where LinkMaster would send repetitive Asynchronous Read requests without waiting for the previous callback to be returned from the underlying server(s). This would cause unnecessary memory usage in the server(s) and increase network traffic if used over DCOM. This issue only affected projects that had set a 'Client I/O Refresh Rate' on one or more link groups. - Fixed issue where the Toolbar and Status bar state was not properly saved when the application is shutdown and the window is minimized. - We now place double quotes around all CSV export fields that contain string data. This allows the application to re-import the same or modified CSV that contained characters that affected the parsing of the CSV file (e.g., commas). - Fixed performance issues when importing a CSV project that references machines and/or OPC servers which are not available but are referenced in the CSV configuration. - Fixed the scaling write issue where an unscaled write would be sent down initially followed by a scaled write, when scaling was enabled and the underlying OPC items were initially added or re- Added due to configuration changes. - Fixed issue with improper 'status' icon updates for link groups/items that contain outputs that failed the add item request. In this case, the icon displayed next to the link item would still show as green vs. gray. - Modified the Quick Browse window to no longer be a TOP MOST window, so that when another application's window is selected, it will fall to the background along with the main LM window. - Fixed anomaly that could occur while the Quick Browse window is displayed and the user obtains access to the LinkItem property dialog (by right-clicking on the application title bar located on the task bar) and issues a close. - Fixed issue that could cause the application to hang if the user attempts to terminate the application while it is in the middle of opening or closing a project. - Fixed issues which delayed the application from terminating in a timely fashion when the project being closed is currently attempting to connect to unavailable machines/servers. - Fixed array write marshalling issues that could occur on some systems. - Fixed link item status issue not reporting that it failed to write to an output item that belongs to a machine or server that is unavailable. - Modified browse filter to use "*" rather than a null string. Some servers do not return all leaves when sending a null string. - Fixed item browser paint issue that occurred if a server returned leaves with no fully qualified item ID.
V2.00.89 March 25, 2005	- Fixed issue where we would not write to link item outputs after receiving a shutdown notification from the server (which owns the outputs)and performing a successful reconnect to the server. This only occurred when write optimizations was set to send last update only. - Fixed issues with not being able to change the machine name on the fly for link item input or output when editing the machine name, rather than selecting something from the drop down control. - Fixed issues with repainting the Quick Browse view if we lose communications with a server displayed in the view. - Fixed anomaly that could occur if LM is shutdown while there is 1 or more event viewer connections outstanding. - Fixed issue where dead value would not get sent to clients and LM link view pane until server reconnect attempt complete. This could take 2 or more minutes if reconnect resulted from network problem. Updates are now immediate upon detection of connection propblem. - Fixed issue where full connection with remote servers could not be established after a temporary network failure. - Added INI File option "Always Browse Servers From Local Machine". This allows LM to connect to OPC servers running on remote machines that cannot run opcenum.exe. The servers must be registered on the local machine, and local machine must be running opcenum.exe. - Enhanced service mode operation. No longer need to start and stop from service manager. Can access from system tray. - Fixed issue where dead value was not being sent to link output items. - Fixed issue where extended demo periods (60 day or longer) were not being honored. - Fixed issue where "Unknown quality" would be displayed in property view if limit bits (in OPC Quality value) were non-zero. - Fixed issue where items with unsupported data type would not be removed correctly. - Added Date data type. - Added license number field in Help/About dialog.
V1.21.76	- Added support for creating Custom Remote Machine references for machines/devices that do not expose themselves through a 'network neighborhood' interface. (76) - Fixed issues with not properly reattempting to establish connections to server(s) if the initial connection partially succeeds (i.e., connect to opcenum succeeds, connect to server fails). (75) - Fixed issues with not properly re attempting to establish connections to server(s) if the initial connection attempt fails. (74) - Fixed byte alignment issue between DDE layer and application layer that was introduced when dead band took scaling into account. (72)
V1.18.71	- Fixed ability to connect to remote inprocess servers.
V1.17.66	- Fixed default project open/save paths to be <product installation>\Projects. - Fixed window flickering issue when performing any operations which invokes a busy dialog. - Added necessary logic to utilize dead banding on scaled values to work with the latest OPC library.
V1.16.64	- Fixed object pointer validation (OPC Layer) to check to see if we have access to the specified memory location, prior to check in the object signature.
V1.13.60	- Fixed issue with browsing internal groups from a client.
V1.12.59	- Increased wait to restart period from 5-30 seconds to 5-600. - Fixed issue with properly observing the restart period.