CPU 317-2 DP Standard CPUs – PLCs – Siemens

CPU 317-2 DP Overview

  • The CPU with a large program memory and quantity framework for demanding applications
  • For cross-industry automation tasks in series machine, special machine and plant construction
  • Used as central controller in production lines with central and distributed I/O
  • High processing power in binary and floating-point arithmetic
  • 2 PROFIBUS DP master/slave interfaces
  • For comprehensive I/O expansion
  • For configuring distributed I/O structures
  • Isochronous mode on PROFIBUS
  • Optionally supports the use of SIMATIC engineering tools

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The CPU 317-2 DP is a CPU with a large program memory. It is used in installations which have distributed automation structures in addition to a centralized I/O. It can be used, for example, as a central controller in production lines or as a machine controller with stringent requirements on machining speed.

It has been optimized in terms of its quantity framework for using SIMATIC Engineering Tools, e.g.:

  • Programming with SCL
  • Sequence control programming with S7-GRAPH

In addition, the CPU offers an ideal platform for simple technology tasks implemented in software, e.g.,:

  • Easy Motion Control
  • The solution of closed-loop control tasks with STEP 7 blocks or the runtime software Standard/Modular PID Control

Extended process diagnostics can be achieved by using SIMATIC S7-PDIAG.


The CPU 317-2 DP is equipped with the following:

  • Microprocessor;
    the processor can handle execution times of approx. 25 ns per binary instruction and 160 ns per floating-point instruction. The CPU 317-2 DP is very powerful regarding processing speed, particularly where word or double-word commands and 32 bit fixed-point commands are concerned.
  • 1 MB work memory (corresponds to approx. 340 K instructions);
    the extensive work memory for program components relevant to execution offers sufficient space for user programs. SIMATIC Micro Memory Cards (8 MB max.) as load memory for the program also allow the project to be stored in the CPU (complete with symbols and comments) and can be used for data archiving and recipe management.
  • Flexible expansion capability;
    max. 32 modules (4-tier configuration)
  • Combined MPI/DP interface;
    the first MPI/DP integrated interface can establish as many as 32 connections simultaneously to S7-300/400 or connections to programming device, PC, OP. Among these connections, one is always reserved for programming devices and another for OPs. A simple network with up to 32 CPUs can be configured with the MPI and “global data communication”.
    This interface can be reconfigured from an MPI to a DP interface. The DP interface can be used as a DP master or as a DP slave.
  • PROFIBUS DP interface:
    The second integrated interface of the CPU 317-2 DP is a pure PROFIBUS DP interface that can be used as a DP master or as a DP slave. It allows a distributed automation configuration with high speeds and simple handling. From the user’s point of view, the distributed I/O is treated as central I/O (same configuring, addressing, and programming). PROFIBUS DP slaves can be operated in isochronous mode on this interface.


  • Password protection;
    a password concept protects the user program from unauthorized access.
  • Block encryption;
    the functions (FCs) and function blocks (FBs) can be stored in the CPU in encrypted form by means of S7-Block Privacy to protect the know-how of the application.
  • Diagnostics buffer;
    the last 500 error and interrupt events are stored in a buffer for diagnostic purposes, of which 100 are stored retentively.
  • Maintenance-free data backup;
    the CPU automatically saves all data (up to 256 KB) in case of power failure so that the data are available again unchanged following voltage recovery.

Technical specifications

Article number


CPU317-2 DP, 1 MB

General information

HW functional status


Firmware version


Engineering with

  • ● Programming package

STEP 7 as of V5.5 + SP1 or STEP 7 V5.2 + SP1 or higher with HSP 202

Supply voltage

Rated value (DC)

  • ● 24 V DC


permissible range, lower limit (DC)

19.2 V

permissible range, upper limit (DC)

28.8 V

external protection for power supply lines (recommendation)

2 A min.

Mains buffering

  • ● Mains/voltage failure stored energy time

5 ms

  • ● Repeat rate, min.

1 s

Input current

Current consumption (rated value)

870 mA

Current consumption (in no-load operation), typ.

120 mA

Inrush current, typ.

4 A


1 A²·s

Power loss

Power loss, typ.

4.5 W


Work memory

  • ● integrated

1 024 kbyte

  • ● expandable


  • ● Size of retentive memory for retentive data blocks

256 kbyte

Load memory

  • ● Plug-in (MMC)


  • ● Plug-in (MMC), max.

8 Mbyte

  • ● Data management on MMC (after last programming), min.

10 y


  • ● present

Yes; Guaranteed by MMC (maintenance-free)

  • ● without battery

Yes; Program and data

CPU processing times

for bit operations, typ.

0.025 µs

for word operations, typ.

0.03 µs

for fixed point arithmetic, typ.

0.04 µs

for floating point arithmetic, typ.

0.16 µs


Number of blocks (total)

2 048; (DBs, FCs, FBs); the maximum number of loadable blocks can be reduced by the MMC used.


  • ● Number, max.

2 048; Number range: 1 to 16000

  • ● Size, max.

64 kbyte


  • ● Number, max.

2 048; Number range: 0 to 7999

  • ● Size, max.

64 kbyte


  • ● Number, max.

2 048; Number range: 0 to 7999

  • ● Size, max.

64 kbyte

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