Working with chromatographic client server

[danielbor]

Dear Forum members,



I would highly appreciate your assistance with the following matter:



Having about 20 HPLC systems in our laboratory, we are interested to switch to a client server system for QC and R&D purposes. I have a few questions with respect to this system:





1. Whether the processing of data takes place within the computer of each device or on the main server. In other words, do we have to invest money on a relatively advanced computer for each HPLC station or would it suffice to use a computer with relatively limited capacities for this purpose.



2. What would be the optimal number of computers to be connected to each HPLC system

[jwmol]

There are many different C/S architectures around. Some have a more "central" approach than others. All variants have their pros and cons. Which architecture fits your requirments best is difficult to answer without more background information.

A central approach is easier to validate if your lab has to be regulatory compliant.

From your questions I assume you want to be as "light" on the client side as possible. One common way of reaching this goal is the use of Citrix server(s) where a central server or server farm takes over the role of presenting the user with the user interface. The physical client will become a "graphical terminal" and can therefore be a very simple PC.

What remains is the way you hook up your instruments to the C/S network. Some vendors' solutions use PC-like boxes. Other vendors use proprietary hardware that can be regarded as a black box. A solution without any moving parts (no hard disks, fans etc.) can be regarded as an optimal solution.

JW
Applied Instruments

[unmgvar]

hello danielbor,

first let me say that in general you should look in former posts on that matter since they hold a lot of information regrding most aspects of moving to a C/S configuration.
most importantly all of your decisions concerning your choice of CDS should be made by a team comprising of at least one person from your IT department and one from each lab, as each and single ne of those units in your firm will require different capabilities from the CDS.

as for your questions:

1. the transfer of the data is the weak point. it is totally dependant upon your company infrastructure. if it is currently bad and weak then the C/S will be full of bugs. the heavier the amount of information that you have to transfer to your central server/s the more risks of something going wrong and loosing the raw data without chance of recovery. i think that it is better to have to handle the raw data after it has been backed up. you want to be able to handle your raw data "locally" in case the net is down. this option will let you also run your machines if you have a serious problem. but you should look at it has a back up option. anyway for the better CDS around the hardware specification for your PC will be easy to handle with common PCs.

2. the optimal number of HPLCs that you can connect to your PC will mostly depend upon the type of connection used and the type of detector
when done with RS232, GPIB and LAN most vendors will tell you to have at most 2 machines. Waters says that you can put up to 4 of their machines on a lace but most of the labs that i know that did it went to having 2 only and the others mainly complain on how it is too fragileto have 4 together.
Dionex claim to be able to have up to 6 of their own hplcs or GCs on one PC but i have never seen it, all other vendors will be not more then 2. also in any case when a PDA detector is in there then you will not have more then 2 hplcs per PC. it is because of the amount of raw data produced by that type of detector
it is also the same for ezchrom elite in general. you can put up to 4 HPLCs but it will mainly be 2 and it has to be a PDA and one more UV.

Check how well the CDS behaves with your own language. Ezchrom elite for example has a lot of bug with hebrew, french and german due to special characters or the use of the coma instead of a dot.
if you can don't have your regional setting on the machines connected to the HPLCs. vendors can't debug all the years of bad programming that the microsoft people have put into their O/S

hope this helps

[Paulhurleyuk]

For most Chromatography data systems, processing the data is done on the local computer. Generally this doesn't need a huge amount of processing power, or,a s has already suggested, you can go for a Citrix or Windows Terminal Server based solution to offload the processing onto a powerfull server.

Important Questions I would ask any vendor:

What does the system do to protect my data between it being acquired and stored against problems with the network, pc's or servers ?

If you're in a regulated lab, how does the system protect me in tersm of regulations ? Can anyone get at the data while its being tranferred to the database ? Or can they access the database remotely ?

How well does the system scale, can you show me a system working fine with fifty instruments and fifty users at the same time ?

How easy is system maintenance, do I have to go to every Pc to update settings, or can I do it via scripts, or a central front end ?

How easy is the system to learn ? The concept of a C/S system suggests lots of instruments and lots of users, with differing experience.

As for me, I would recomend you look at Chromeleon from Dionex. We run over twenty instruments and fourty users, and have run five instruments off one PC at a time (although not recomended, if the PC has a problem it affects five instruments !)

Paul.

[DR]

For at least 2 such systems (Empower, TotalChrom), the data is stored locally until it can be cleanly sent off to the server. Both systems can be run on a Citrix server or with local client stacks. Each has its own pros and cons and can be easy or a chore to patch depending on how it is set up and how good your particular network is set up.

As far as hardware goes, TotalChrom relies on the NCI which can simultaneously acquire 1 or 2 analog signals from a detector. NCIs contain a networked data buffer fed by a analog/digital converter. They can also be used to control instruments to some extent via remote switches (I think real instrument control requires another box). Generally, the ratio of NCI:detector is 1:1. With Empower, you have LAC/Es and SAT/INs. LAC/Es are computers that buffer and retransmit data to a server. They also provide a means of instrument control for Waters and Agilent instruments via GPIB/IEEE (Waters except Acquity) or serial +/or Ethernet for (Agilent & Waters Acquity instruments). Other instruments employ a SAT/IN box to handle the analog conversion before the LAC/E gets the data. LAC/Es can each handle more than one instrument (totals vary as a function of the instrument types and numbers of each type). LAC/Es are more expensive than NCIs but they can do more.

Other vendors offer similar solutions but I'm not up on the details for them (Thermo, Agilent, Fisons, EZ Chrom, Chromeleon to name a few).

As with instruments, all recommendations must be taken with a grain of salt until you have had a chance to meet the people who would be helping you through the transition to a new system (always somewhat painful). You should also talk to the local competition in your own industry and find out what they think of the vendors that serve your area.

[ntruong]

It depends on how busy you are with 20 LCs. If 20 LCs are to be used most often, I would spend money on advanced computer for each workstation.
I agree with Paul on the downside of having multiple instruments connected to one PC. If something happens to the PC or any instrument that connected to it, you are most likely have to repeat the run. At our lab, we have two GCs connected to one PC and another set of two LCs connected to one PC and we are paying a dear price for it, if you know what I mean. By the way, can you spare to have analysts sitting around waiting for the other analyst processing data because you have a very limited workstation to work at?

[danielbor]

Hello


Thank you veru much for your assistance.