Is thin-client the answer?

ControlDesign.com

In this installment of The Answer to Your Problems, CONTROL DESIGN readers weigh in on whether to take a thin-client approach as an alternative to other workstations in a harsh manufacturing environment.

e'll be responding soon to an RFQ to Supply updated operator terminals and control stations for a train of industrial machines. The customer wants the ability to present multiple applications and multiple-machine monitoring simultaneously and provide on-site monitoring and diagnostics that includes interactive maintenance files and even video and audio. We think we should pursue a thin-client approach. Any advice?

-- From the August issue of CONTROL DESIGN magazine. 

THE ANSWER TO YOUR PROBLEM:
Thin Is PHAT
Two-and-a-half years ago I introduced thin clients to all non-NC machine tools in our metal forming shop as part of a move away from paper. The thin clients have performed exceptionally well, with only one failure over the past 30 months. Thin client has allowed us to eliminate the scrap previously produced by manufacturing based on obsolete drawings, by delivering the current electronic drawing files to each machine station instantly.

Training is a virtual non-issue. Each station was given a generic username and a null password. The operator simply turned on his monitor at the beginning of his shift. The stations were given read-only network permission, and ran a free CAD drawing viewer on a Windows platform installed on the network server. The only icons available were a file manager, an Internet browser, Acrobat Reader, a proprietary shear list program, and the CAD viewer.

Part numbers were already filed under an intuitive alpha-numeric file structure by the engineering staff. File extensions were set-up to default to the appropriate programs, so the operators only had to find the part file in the file manager and double click its icon.

Shear operators view the cut list on the proprietary program and then shear and label the required flat blanks. CNC punches automatically load the part program by part number; non-NC punch operators view the flat-pattern engineering drawing and proceed the same as they did when paper records were used. Forming operators also open and view the engineering drawings to find back-gauge settings and forming instructions. Photos and additional instructions are included in each part folder as required, so additional assistance is available by simply double-clicking on the appropriate icon. The internet browser is used to view photos, and the Acrobat reader opens .PDF files containing additional instructions.

Network cabling was already present in the machine area to run the CNC punch presses and the supervisor's workstation; individual terminals were simply spliced in. Metal boxes were fabricated in-house to protect the thin client [workstations], support the monitors (inexpensive CRTs), and provide a surface to use the mouse. The set-up was handled completely by our in-house IT department, and is no more complicated than setting up a workstation that runs network copies of any other software.

I would highly recommend the thin client [approach] as a robust and inexpensive alternative to other workstations in a harsh manufacturing environment.

Jim Reil, PE, NSPE, Business Development Engineer, H&K Dallas Inc.

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Ask These Questions
The application of thin clients requires further consideration in this situation. There are many details that need to be clarified before a good decision can be made. Some key questions to answer include:
• How many terminals would be installed at launch and are their possible future expansion plans?
• What software is going to be used and does it support terminal services efficiently?
• Will machine displays include significant animations? 

All of these questions will help figure what the overall network load might be. If the terminals are to provide both extensive viewing/observing features and control features, the priority of the control features must be carefully considered.

You wouldn't want Machine X crashing because an operator somewhere was viewing some graphics-intensive application. Maybe a solution could involve two separate thin client networks. I would hesitate to send too much video or audio across a thin client network that has control responsibility. Not only will this tax the server, it will load down the network. I've seen some literature on efficient transfer of video to thin clients, but I haven't had a reason to test this out.

I don't believe that there is anymore training involved with thin clients than a standalone PC network. Your core engineers and IT personnel need to understand what goes on in the background, but in general, most of the environment is transparent to the operator. 

There is a definite need to be very diligent in setting security settings for users that will logon from thin clients. Otherwise, you will end up with plant floor operators deleting files on your precious servers or drawing obscene pictures in Paint. This, though, isn't impossible--in fact, it's fairly easy to restrict your thin-client users to having almost no rights and then open up rights as they are needed.