What SCADA package best fit for WAN?
Most SCADA packages choke because of too-fast update stream coming from the server/s
over slow data-link lines connecting the WAN.
(local station need 1 sec update rate from PLC, remote viwers need only 10 sec
update rate)
Thanks

 

First, group your data together in the PLC to minimum the number of reads and writes. If you try to read data scattered all over the PLC memory then you will have to do a lot of reads and this will take longer to read all of the data.

We prefer Visual Basic for SCADA since you can easily throw the Winsock control into the master and create slaves (also in VB) that have winsocks that connect to the master. Build a user defined data type to hold all of the data and then use the copy memory API to copy this into a character buffer to send out the socket. It's simple, we have examples on our website.

Keith Baldwin
www.HTServices.com

 

The most efficient SCADA software that will work over any WAN link is Cygnet. Cygnet is running over 64k frame relay circuit, and the performance is outstanding. Since it only communicates in 4k packet sizes, it is very miserly on bandwidth consumption. We even tried to detect its presence on the network using a sniffer, and while it was running, the bandwidth it used blended in with the noise on the system. That is how effecient Cygnet is with the communication protocol over LAN/WAN links. Feel free to contact me about testing that we did with the Cygnet product. - "[email protected]", mailto:[email protected]