Networked chromatograph - what does it mean and how to make it.

Introduction

This article is intended for those who interesting in building networked analytical environment and any laboratory automation issues.

Name the things

Fist of all - lets name the things:

• Networked chromatograph - chromatographic analytical instrument which interacts with analytical software through local area / wide area network
• Network - any media carrying TCP/IP packets. For instance - generic 802.x Ethernet.

For simplification lets assume that Networked Chromatograph (NC) is a device with RJ-45 outlet, which can be connected with UTP cable to network equipment or directly to computer. This article focuses mostly on GC instruments, but for LC devices there are no exceptions from stated propositions.

Advantages

What advantages give us the Ethernet connection over others RS-232, HPIB, USB, INET...?

• Technical issues about why Ethernet+TCP/IP is better than other connection methods is out of this article flow.
• Ethernet and TCP/IP are the INTERNATIONAL STANDARDS de jure et de facto
• You don't have to know exotics like HPIB addressing or RS-232 bitrates. Just do to your network admin and say him(her) - "I got a new instrument. Please, connect it to network."
• There should be solutions for problems like:
  • "Where to connect another instrument?". The answer is single and simple - "To Network!".
  • "My computer is out of RS-232 ports or have not RS-232 ports at all".
  • "I just installed Windows XP or Windows 10, why my cool HPIB board is unsupported?"
  • "I`m suffering from that old PS/2 computer, but my cool HPLC instrument works only through specially designed MCA-bus interface". This is a special case and should be considered separately.
• Your cabling problems are ENTIRELY your COMPUTER DEPARTMENT DUTY but not NOT YOURS.
• RS-232 cable from Shimadzu Corp. some dealers sell at $100 !? Not funny if your technician occasionally breaks it.
  UTP cable costs $0.25 per meter + 2 jacks x $0.25
• NC instrument can be located not only in nearest building but on the other side of our planet.
• When your instrument runs a big sample sequence, it would be nicer to sit in clean and silent office and look at screen with results, but not hearing for hours for sampling machine noise sitting near the instrument.

The real NC instruments

Nowadays NC instruments going to be presented wider and wider at the market.
Historically the first NC was the Agilent / HP-6890 Plus with HP JetDirect MIO board installed. The most modern version of 6890 family is Agilent 6890N which have Network adapter built into. There are other instruments with same feature - Varian CP3800,3900 and ... no more.

The idea of NC instruments

What to do with other instrument types? Connect a computer to each pair of instruments? Probably there is more elegant solution. Have any analyst heard about terminal servers? Sounds like a word from UNIX world. Generally it is a small box with several RS-232 connectors and single Ethernet connector. This device has the same functionality like HP JetDirect card mentioned above. The idea is - when our instrument producer had not included Ethernet support into instrument box, we can attach it externally to instrument RS-232 port. Typically 8-port terminal server costs about $1000 - not a good idea, computers have the same cost. But port servers are different e.g. 1-port Digi One port server (www.digi.com) costs about $200 (maybe even less when you buy some of them). So connecting RS-232 instrument to TCP/IP network is consist of:

• Connection your GC instrument to single-port server
• Connection your port server to TCP/IP network

The connection of the chromatograph to TCP/IP network can be done not only by hardware means but the software solutions can make this for 0$. The software port switcher called PortSwitch is ready to do this.

Why this is important?

When the laboratory has the only analytical instrument, such questions would not even stand for you. But the real life examples lead to solutions, which have been discussed above.
For example, one of laboratories of Grodno JS "Azot" has the following instrumental park:

• Crystall-2000M - 3 pcs.
• Tsvett-800 - 2 pcs.
• Tsvett-500 - 2 pcs.
• Tsvett-100 - 2 pcs.

So for entire farm support we have to use 6 serial port - 3 for Crystall-2000M, 2 for Tsvett-800 and one for LabNET bus. The total cable length would be about 100m. Evidently each of the instruments should be connected to network!

Another example - HP-6890, connected through 82335 HPIB board to computer. The board 82335 HPIB is supported only under Windows 9x and Linux (:o)). The instrument was upgraded with HP JetDirect MIO board and converted to Agilent / HP-6890 Plus. Now this instrument can be controlled through network from any computer either from UniChrom as from ChemStation.

Conclusions