Thin Client Terminal Servers with Scada

[Rod_Hackney 2]

We are discussing the use of Thin Client Terminals instead of plant floor PCs at one of our facilities that uses Wonderware. Wanted to know if anyone has implemented this type of system and the pros/cons they encountered.

[BobLfoot 301]

We just installed a Wonderware System using Terminal Servers and Thin Client terminals. It has worked quite well. Instead of needing 10 Wonderware licenses for 10 locations we need 2 licenses ofr the terminal servers. We are chasing a couple of minor problems right now. 1. Occasionally the clients "hang up" with a Blue Screen of Nothing {BSON} and we have to use our client manager software to restart them. 2. Out CLient Manager software is supposed to support remote viewing and control of terminals. The viewing works well but the cotnrol is iffy. Been using Remote Desktop when we need remote access and control.

[Rod_Hackney 2]

Thanks, I will keep this info in mind if we end up going with thin clients

[Nathan 7]

I could have sworn that the Wonderware licensing requires you to purchase per concurrent seat thin client (Remote Desktop/Terminal Services) licenses. You have the benefit of counting concurrent users instead of installed seats, but still are subject to a client licensing model. Also, this may or may not be totally relevant, but...at my workplace we use thin client terminals that run on Windows 2003 servers. They are subject to the Microsoft concurrent licensing - I think they're sold in 25 packs. In any event, we've run into licensing problems on multiple occasions. In one case, after we took the servers down for maintenance for the weekend (a power failure would cause a similar thing), each thin client grabbed a second license. You cannot delete license leases by design. This means that you have to wait until they expire or "add licenses" - which can be done without purchasing them, but shouldn't unless it's an emergency. The second case occurred where we had a "rogue" terminal that had about 15 licenses. We haven't determined if it did so every reboot or what. We were not able to pull up the IP or MAC address when the device was off. Luckily, our naming convention included the serial number of the unit, which we tracked in a spreadsheet. This was caused by a misconfiguration - the unit had to be reprogrammed (flashed again). Don't get me wrong - I love thin clients. I just wanted to point out a few things to consider: 1. From an IT perspective on the client end they're much easier to support than PCs. This is especially true if you have a lot of applications to maintain that constantly change version (ie your organization really uses many MS Office apps). You lose a lot of that benefit if you're only running one application that doesn't change much (ie, an HMI). They still have less parts that can fail and are cheaper/easier to replace in such an event. 2. From an IT perspective they're not magical. You will have client issues and there is server management to be done. Clients are very dependent on all the networking services being up. Also, they're surprisingly efficient considering what's going on, but the model isn't as scalable as your client/server model. How many 500+ seat thin client networks have you seen? 3. I'd recommend thoroughly investigating server "client licensing" from both MS and WW. You're likely to get double whammied on that. Will someone please verify this. Thin clients are a cool technology that certainly has a place! Just know what you're getting into and that, like any technology, it isn't a "magic bullet". Edited 16 Oct 2007 by Nathan