john paley said:
!00 data is a broad term. do you mean a hundred dada points?? How often do they want the data collected and stored? Once a second? If so, that's 600/minute, 36000/hour, 864000/day. 100 turns into a lot very quickly. even more if they want a time stamp.
The answer to save the data is memory. But you have to decide how much data you want and how much memory is available to store that data. Use fifo's so the stored data is "rolling" with time.
Then you configure the system to always store and display this data, wheather the workstations are up or down.
John, currently they are logging the data in the wonderware workstation every second. Yes, i know there is a lot of data for PLC size memory, but for workstation it should be fine since our harddrive nowadays are around 500Gigabyte each, this should be enough for a few years.
"Then you configure the system to always store and display this data, wheather the workstations are up or down." Can you please explain on this? The "system" you mean is the PLC? The customer is looking for a system which is able to save the data for a few days when both the wonderware workstation is down.
rPraveenkum said:
Have a redundant Scada system this will solve your purpose.
rPraveenkum, what if both the workstation are down? The chances for workstation to down is higher than redundant PLC to down, am I right?
n_lev said:
If your communication line is reliable I would take a look at Wonderware InSQL. First of all it can store date independently of status of SCADA. And it also has a "Store and Forward" service that can save data even if InSQL is down and forward data to it once it is back online. This service can be even run on a remote PC which can be specificaly dedicated for this purpose...
If you have many PLCs in different locations it might be pretty big job to enable each one of them to log data (especially if they are different). InSQL will allow you to do all logging within a day and without any travelling and any changes to existing PLCs.
Marc said:
I agree, set up a seperate computer on the network and use it to run INSql from wonderware (basically an overlay for customizing MSSQL). Lock it up and don't even put a monitor or keyboard on it once your set up.
It will do what you need it to do and can fail back and forth between whatever i/o d-a servers you might be using to collect info for intouch. Give it a big UPS as well.
n_lev/MarC, the communication line is stable & fast (4Mbits). From I understanding, there is a seperate workstation running InSQL, can we run redundant InSQL? So the existing wonderware will grab data from the InSQL instead of PLC directly?
InSQL is from Wonderware? Sorry, not familiar with wonderware thingy.
Oakley said:
I would be looking at putting in multiple servers utilizing Archestra. Archestra can be redundant, as well as if you have multiple strategically placed servers, the data can be stored and forwarded to the InSql data historian.
Oakley, multiple server means more than 2 servers running redundantly? What's the purpose of running Archestra with InSQL? I taught INSQL is able to log all the data from all treatment plant (not sure if INSQL can run redundant)? Price wise should be okie, what they asking for is a reliable system.
JohnW said:
How does that saying go?
"wonderware the data went?"
When the wonderware workstations are down, all data send from PLC will not be captured & display. so if the wonderware workstations down for 6 hours, all data within that 6 hours will be lost! They cannot afford to let this happen.
1) So, based on the replies, we can summarize that the only way to prevent data lost when wonderware workstations are down is by using another set of redundant workstation running INSQL?
2) BTW, has anyone come across a korea brand PLC which has 64MB memory built in, called CIMON? Based on the info given by our customer, this PLC is able to do data logging with it's memory size, not too sure how reliable is this PLC. Does AB has something like this??