Easy Veiw Data Logger To SLC500

ian.smith7

Member
Join Date
Aug 2002
Location
UK
Posts
145
Hi All
I have been working on a project which involved modifying an EasyBuilder (MT8000) project used to log data from several SLC5/05 64K PLCs connected via Ethernet in the same panel through 1 switch.
My project involves the logger grabbing data from two of the PLCs at On<>OFF transition every second. Then logging it at 2 second intervals. When I download the Logs the Data is repeated for at least 2 consecutive records giving me a minimum definition of 4s. This is not as fine as I would like and surprised me. I have made several changes to the program to get it that fast it originally was minimum 6s.
Am I expecting too much of the system.
Thanks
Ian

Here is some info about how the system is set up.
The PLCs are set to service comms immediately (S:2/15=0)
A macro grabs the data from various PLC data regs and writes it to consecutive local data words in the data logger. The macro is triggered by LW_Bit-0901701 transition ON<>OFF.
The Data log object records the data from the local memory every 2 seconds.
 
My project involves the logger grabbing data from two of the PLCs at On<>OFF transition every second. Then logging it at 2 second intervals.
Try it this way: Only have the logger grab data every 2 seconds. Then log it at 2 second intervals. That will be more likely to work.
 
try using the Data Transfer (Time Base) instead of the Macro. Maybe set your rate at .05

It sounds like your data is not being updated by the macro before your log. Because you said you get repeated values. The Time Base of the Data Sampling is using the same system clock that is running the macro. So both are trying to run every other second at the same time and your logging the second time before the macro runs to update your values.

at least that would be my guess.
 
Hi thanks for the replies.
The Data Sampling requires a different routine for every non contiguous data set. So I think the OEM has used the Macro to consolidate the data into contiguous sets as they did not have access to the PLCs when the data logger program was written.
I have been considering consolidating the data required in the PLCs then Data sampling direct to the PLC and cutting out the macro altogether.

I agree that the duplicate logs are due to a mismatch of the macro and data logging time base triggers.

Just Been reading a Help file I found on the web.
There do seem to be some user settable memory bits in the data logger that can be set and reset from a macro and used to initiate the data sampling routine. So I think I will give that a try.

thanks for your suggestions
Ian
 
it would be possible to align data into LW by using the Data Transfer by assigning each PLC tag to a LW aligned array. Then Use Data Sampling on the LW's. But the method you mentioned sounds good. I seem to remember reading something similar about that in the help file. If you would could you post a link to the article you are referring to I would be interested in reading it myself. Thanks and good luck with your project!
 
The Article I found is Here http://plctouch.com/EB8000Downloads.html
In the chapter 18 PDF Page 29. The SetBitOn and SetBitoff Functions.

I'm Hoping to Set/Reset LB9000 to 9009. The help file I have says they are Read/Write (R/W) from a macro but I also get the impression they are reserved (?). so I will have to try it and see when I get to work on Thursday or Friday.
Ian
 

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