Monday, August 8, 2011

Logix Architecture PLC-5 and SLC 500

Input and outputs
The processor of PLC-5 and SLC 500 map memory of I/O into data table files of I and O. The data of I/O is keep informed synchronously to the scan program so you recognize you have present values every time the processor starts a scan. A controller of Logix indications I/O which is updated asynchronously to the scan of logic. Use the instruction of CPS (synchronous copy) to make a data buffer of I/O to utilize for fixed values through execution of logic and update the buffer as wanted for a controller of Logix. You have to add instructions to copy the data of I/O into the arrays of I and O after the conversion is finished. Perform this at the starting or ending of a program to buffer the data so that it is accessible synchronously to the scan of program.

The processors of PLC-5 and SLC 500 save all data in the tables of global data. You entrée this data by identifying the data address you want. A controller of Logix supports data that is local to a program and data that is worldwide to all the jobs within the controller. A controller of Logix can also distribute data with other controllers, and rather than addresses, you utilize tags to access the data you desire. Each data table file of PLC-5 and SLC 500 can save some words of associated data. A controller of Logix utilizes arrays to save associated data. The tool of translation converts the data table files of SLC 500 and PLC-5 into arrays of Logix.

The timers of PLC-5 and SLC 500 are depending on their architecture of 16-bit and can contain dissimilar time bases. A controller of Logix is based on its architecture of 32-bit and only supports a 1 ms time base. The tools of translation convert the timers of legacy as they best fit into the architecture of Logix. Converted timers may need rework to guarantee they run correctly.

The processor of PLC-5 supports the instructions of block-transfer write and read (BTW and BTR), MSG (message), and CIO (ControlNet I/O) instructions. The processor of SLC 500 supports the instructions of MSG. The controllers of Logix support the instructions of MSG. The tool of translation converts the legacy instructions of BTW, BTR, and MSG into the instructions of Logix MSG. Any instructions of CIO are not converted. You have to organize the instructions of MSG so that they operate properly and rework any instructions of CIO once you import the converted logic.


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