Siemens Simatic S7-300 Technical Data Manual page 8

Table of contents
4 Memory concept ..................................................................................................................................... 4-1
4.1 Memory areas and retentivity..................................................................................................... 4-1
4.1.1 CPU memory areas.................................................................................................................... 4-1
4.1.2 Retentivity of the load memory, system memory and RAM....................................................... 4-2
4.1.3 Retentivity of memory objects .................................................................................................... 4-3
4.1.4 Address areas of system memory ............................................................................................. 4-5
4.1.5 Properties of the Micro Memory Card (MMC) ............................................................................ 4-9
4.2 Memory functions..................................................................................................................... 4-11
4.2.1 General: Memory functions ...................................................................................................... 4-11
4.2.2 Loading user program from Micro Memory Card (MMC) to the CPU ...................................... 4-11
4.2.3 Handling with modules ............................................................................................................. 4-12
4.2.3.1 Download of new blocks or delta downloads ........................................................................... 4-12
4.2.3.2 Uploading blocks...................................................................................................................... 4-12
4.2.3.3 Deleting blocks......................................................................................................................... 4-13
4.2.3.4 Compressing blocks................................................................................................................. 4-13
4.2.3.5 Promming (RAM to ROM) ........................................................................................................ 4-13
4.2.4 CPU memory reset and restart ................................................................................................ 4-13
4.2.5 Recipes .................................................................................................................................... 4-15
4.2.6 Measured value log files .......................................................................................................... 4-17
4.2.7 Backup of project data to a Micro Memory Card (MMC) ......................................................... 4-19
5 Cycle and reaction times......................................................................................................................... 5-1
5.1 Overview .................................................................................................................................... 5-1
5.2 Cycle time................................................................................................................................... 5-2
5.2.1 Overview .................................................................................................................................... 5-2
5.2.2 Calculating the cycle time .......................................................................................................... 5-5
5.2.3 Different cycle times................................................................................................................... 5-8
5.2.4 Communication load .................................................................................................................. 5-9
5.2.5 Cycle time extension as a result of testing and commissioning functions ............................... 5-11
5.2.6 Cycle extension through component-based automation (CBA)............................................... 5-11
5.3 Response time ......................................................................................................................... 5-14
5.3.1 Overview .................................................................................................................................. 5-14
5.3.2 Shortest response time ............................................................................................................ 5-16
5.3.3 Longest response time............................................................................................................. 5-17
5.3.4 Reducing the response time with direct I/O access................................................................. 5-18
5.4 Calculating method for calculating the cycle/response time .................................................... 5-19
5.5 Interrupt response time ............................................................................................................ 5-21
5.5.1 Overview .................................................................................................................................. 5-21
5.5.2 Reproducibility of delay interrupts and watchdog interrupts .................................................... 5-23
5.6 Sample calculations ................................................................................................................. 5-24
5.6.1 Example of cycle time calculation ............................................................................................ 5-24
5.6.2 Sample of response time calculation ....................................................................................... 5-25
5.6.3 Example of interrupt response time calculation ....................................................................... 5-27
6 Technical data of CPU 31xC................................................................................................................... 6-1
6.1 General technical data ............................................................................................................... 6-1
6.1.1 Dimensions of CPU 31xC .......................................................................................................... 6-1
6.1.2 Technical data of the Micro Memory Card (MMC) ..................................................................... 6-2
6.2 CPU 312C .................................................................................................................................. 6-3
6.3 CPU 313C .................................................................................................................................. 6-8
6.4 CPU 313C-2 PtP and CPU 313C-2 DP ................................................................................... 6-14
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CPU 31xC and CPU 31x, Technical data
Manual, Edition 08/2004, A5E00105475-05