Features Of The Position Module - Siemens SIMATIC S7-200 System Manual

Features of the Position Module

The Position module provides the functionality and performance that you need for single-axis,
open-loop position control:
Provides high-speed control, with a range from 20 pulses per second up to 200,000 pulses
-
per second
Supports both jerk (S curve) or linear
-
acceleration and deceleration
Provides a configurable measuring system
-
that allows you to enter data either as
engineering units (such as inches or
centimeters) or as a number of pulses
Provides configurable backlash compensation
-
Supports absolute, relative, and manual
-
methods of position control
Provides continuous operation
-
Provides up to 25 motion profiles, with up to 4
-
speed changes per profile
Provides four different reference-point seek
-
modes, with a choice of the starting seek
direction and the final approach direction for
each sequence
Provides removable field wiring connectors for Provides removable field wiring connectors for
- -
easy installation and removal
You use STEP 7--Micro/WIN to create all of the configuration and profile information used by the
Position module. This information is downloaded to the S7-200 with your program blocks.
Because all the information required for position control is stored in the S7-200, you can replace a
Position module without having to reprogram or reconfigure the module.
The S7-200 reserves 8 bits of the process image output register (Q memory) for the interface to
the Position module. Your application program in the S7-200 uses these bits to control the
operation of the Position module. These 8 output bits are not connected to any of the physical
field outputs of the Position module.
The Position module provides five digital inputs and four digital outputs that provide the interface
to your motion application. See Table 9-8. These inputs and outputs are local to the Position
module. Appendix A provides the detailed specifications for the Position module and also includes
wiring diagrams for connecting the Position module to some of the more common motor
driver/amplifier units.
Table 9-8 Inputs and Outputs of the Position Module
Signal
STP
RPS
ZP
LMT+
LMT- -
P0
P1
P0+, P0- -
P1+, P1- -
DIS
CLR
Description
The STP input causes the module to stop the motion in progress. You can select the desired
operation of STP within the Position Control wizard.
The RPS (Reference Point Switch) input establishes the reference point or home position for
absolute move operations.
The ZP (Zero Pulse) input helps establish the reference point or home position. Typically, the
motor driver/amplifier pulses ZP once per motor revolution.
LMT+ and LMT- - inputs establish the maximum limits for motion travel. The Position Control
wizard allows you to configure the operation of LMT+ and LMT- - inputs.
P0 and P1 are open drain transistor pulse outputs that control the movement and direction of
movement of the motor. P0+, P0- - and P1+, P1- - are differential pulse outputs that provide the
identical functions of P0 and P1, respectively, while providing superior signal quality. The
open drain outputs and the differential outputs are all active simultaneously. Based upon the
interface requirements of motor driver/amplifier, you choose which set of pulse outputs to
use.
DIS is an open drain transistor output used to disable or enable the motor driver/amplifier.
CLR is an open drain transistor output used to clear the servo pulse count register.
Open Loop Motion Control with the S7-200
Figure 9-9 EM 253 Position Module
Chapter 9
265