System design for remote control

[alex.]

I just wonder which tech of ni I should use.

My system is one data center and some remote DAQ site. The communication is through WAN.

It need to

- start stop and schedule DAQ card from remote data center

- send realtime data back for display

- report the DAQ running status, such as online.

- send history data from site pc to center database 

there are many choice, such as tcp/ip, data socket server, shared varible, remote panel, remote vi server, web server.

May I know which one is more fit for the application?

Thanks a lot.

[RavensFan]

I think a 2 VI approach would work best.  One VI running on the remote PC.  The other at the data center.  Commands would be sent back and forth by way of shared variables.  (Then it is a question of which PC to host the shared variables on, I would recommend on the remote site PC).  Data could be sent back by way of buffered shared variables.  That, or using one of the other network technologies such as TCP or FTP to send back a batch file of data.

I like the idea of the remote web panel.  And that would work for your first 3 requirements.  But would not work for getting data stored back on you data center PC since in this case, the data PC is just acting as a terminal to view and control the remote PC.  However, one of the choices (TCP or FTP) could get the data sent back to the data center PC.

One other question to ask yourself is whether you just need one data center PC to communicate with the remote site (in which case the two VI setup would work) or if you want to access the remote site from multiple PC's (in which case the remote web panel might be better.)

[alex.]

One other question to ask yourself is whether you just need one data center PC to communicate with the remote site (in which case the two VI setup would work) or if you want to access the remote site from multiple PC's (in which case the remote web panel might be better.)

The case is at least one pc in data center can control all the remote site pcs.

The remote site pc itself can control itself.

Other pcs in data center can at least view the data, whether can send command down to remote site may due to authority right, that is what I am thinking of.

[RavensFan]

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The case is at least one pc in data center can control all the remote site pcs.

The remote site pc itself can control itself.

Other pcs in data center can at least view the data, whether can send command down to remote site may due to authority right, that is what I am thinking of.

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I think the best bet would be to use the remote front panels web option.  That way any of the data center PC's could connect and control.  (Otherwise you would need to have a user interface VI on each of the data center PC's, and work out a scheme that prevents conflicts if more than one tries to control the machine at once.  The remote web panels have this already built in.)

Then for uploading historical data to the data center, just need to use a TCP/IP protocol for sending data or FTP: commands.  (Assuming that this is a data file of some sort that needs periodic backing up.)

[krishh]

Hi all,

I am very new to Labview, but I have to deal with somewhat difficult problem of remotely controlling the Laser in next room. The PC I will be using has already built labview software to control the laser if laser is closeby. But the laser is next door (~200-300 feet), and the PC which controls the laser also have the labview software to control the laser. Please suggest me how should I start communicating from my first PC to the laser (may be using the laser labview software or not). To start with I would be glad to find some reads or demonstrative examples or any suggestion which will head me to right direction.
I hope for great help.
Regards
Krish

[RavensFan]

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@krishh wrote:
Hi all,

I am very new to Labview, but I have to deal with somewhat difficult problem of remotely controlling the Laser in next room. The PC I will be using has already built labview software to control the laser if laser is closeby. But the laser is next door (~200-300 feet), and the PC which controls the laser also have the labview software to control the laser. Please suggest me how should I start communicating from my first PC to the laser (may be using the laser labview software or not). To start with I would be glad to find some reads or demonstrative examples or any suggestion which will head me to right direction.
I hope for great help.
Regards
Krish

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It would probably be a good idea to start a new message on this rather than continue in this message thread.  It seems to be a different situation you are asking about then what the original poster was doing.

How does the PC communicate with the laser if it is close by?  Is it a serial connection? ethernet connection?  GPIB?  something else.  If it is serial, is it RS-232, RS-485, USB?   200-300 feet is too far for an RS-232 or USB connection.  But there are numerous products on the market that will adapt those serial protocols to either an RS-485 wiring setup, or put it out over an ethernet connection.  So you can go RS-232 to RS-485 on one end.  RS-485 goes to 4000 feet (depending on baud rate).  Then on the other end another adapter converts it back to RS-232.  I have also used a remote USB hub that connects to a LAN connection, and with driver software installed on the PC, it turns that remote connection into virtual serial port connections.

These are good devices that have worked for me.  But if they would work for you all depends on how the PC connects to the laser now.

[krishh]

Sorry for replying in somebody elses thread, actully I intended to creat new thread, but when I was registering I was in this thread so it posted it direclty to this thread. Moderator, if possbile please move it to the right place.

Any way, Thanks Ravens Fan for the suggestions. My computer communicates through GPIB (IEEE484) to laser. At this point I am thining of avoiding communication through the long wires, to avoide any possible delay in data transfer or corruption. The other option I am planning to adopt would be to control the PC from my room to PC in laser room, through some communication interface availabe through NI. Please let me know if that is a possbility and how to head towards it.

Regards

[RavensFan]

You can definitley do that.  The use of shared variables would be a quick, easy way to get started.  I would host the shared variable library on the PC that is controlling the laser and let it handle the direct communication with the laser.  The software on the remote PC would just write the required control data into the shared variables and read in any data that might be feedback.

Another possibility and might be the easiest to implement is to just use the software as you are using it now on the directly attached PC.  But publish the VI to the remote web panel system.  The remote PC would then log into the first PC's web server and can request control.  It is basically like controlling the PC as if you were sitting at it, but doing it through a web panel interface.

You can also write your own communication protocol using TCP/IP commands, but if it was my project, I would do either of the first two choices.

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@krishh wrote:
. My computer communicates through GPIB (IEEE484) to laser. At this point I am thining of avoiding communication through the long wires, to avoide any possible delay in data transfer or corruption.

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I don't know what is the distance limitation for GPIB.  Obviously, if it is longer than that it won't work.  But if it works, there shouldn't be any delay.  The risk of the methods of communication using the network is that there could be delays in communication depending on network traffic.  So the PC to PC connection could have network errors or delays.