By Jeremy Pollard, CET, Columnist
DO YOU NEED multiple HMI/computer stations for the machine applications you install? Do you have to use SQL for data logging? What about merging the machine data with your customersÂ’ networks? And who maintains the systems?
Easy answers, are they? The question that scares me the most is the last one. Warranty periods range from one to three years, and companies use warranty and support terms as a front-line selling tool. Support costs might be increasing over time, but one thing is certain—support will increase by the square of the number of PCs supporting the system.
Analyst firm Frost & Sullivan estimates the cost of supporting a desktop in an IT environment at $1,200 per year. This might not be anywhere close to the support costs for PCs on the factory floor, and, if theyÂ’re tied into the plantÂ’s network, it could be higher.
So how can we do better in both performance and cost?
Many of you know about thin-clients, a connectivity method frequently used in the commercial IT world. A thin-client uses resources locally to connect to the network, display graphics, and interface with the user via keyboard and mouse. IÂ’m thinking that most suppliers want to sell you computers, not thin-clients, so a number of you still might now know about its application on the factory floor.
The thin-client logs into the server, and requests a “session.” During this session, the user has access to all applications residing on the server to which the administrator gave him permissions. A quick summary of thin-client’s benefits include:
- The administration of the system is done on the server, not the client. And it can be done from anywhere, assuming Internet access.
- You no longer need industrially hardened computers. With no rotating devices or fans, the maintenance on a thin client is minimal. Should one fail, replacement is pretty low cost. No configuration typically is necessary.
- Depending on your application, Linux-based clients can be used.
You also could have wireless clients just as easily, and having a mobile thin-client is an easy add-on. Machine mobility is attained with minimal expense and configuration.
On the server side, you have a couple of options. You need the hardware, of course, and you need to decide what applications you’ll be running. Typically, you’d be running PLC programming software and/or HMI software—both with run-time protection.
Also, you could run Terminal Services (TS) on the server from Microsoft (if yours is a Microsoft world). This is worthwhile if you run typical Windows-based applications such as Word, Excel, data logging interface, etc. TS uses hardware resources as Windows would use them, such as performing caching and interrupt management. Speed would be good.
In the industrial world, however, things are rarely “normal” regarding the type and variety of clients’ applications needed. So something called “virtualization” might be what you want to consider.
In a virtualized environment, hardware management is separated from software management, and equipment can be treated as one processing pool. Virtualization server software is installed on a Windows-based server, and is administered from there. The clients on the floor now can be varying devices running various software administered from the server side. Consequently, you have multiple “virtual” servers, each with their own virtual CPU, memory, and storage, but running on one real machine, providing services to a variety of factory-floor clients.
The server costs in both environments are the largely the same. I used VMWareÂ’s virtual server for this comparison, which it gives away for free. VMWareÂ’s server allows multiple sessions on a computer using the host-operating system. This means the host operating system is also virtual for each client, so software licensing costs are effectively the same.
VMWare says, when the thin-client connects to the virtual server, an ActiveX control or Java applet is automatically downloaded to connect the client to the server. The administrator set up the user previously.
Support costs now are focused on the server alone. And you have options beyond a conventional thin-client environment.
Can you envision some value in a solution where these customer-installed thin-clients were accessing data and solutions from your server over the Internet? Tell me how this might help you. A new world awaits.
