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Low Cost Automation Tutorial

#041 Motion Mechanism Design - 11 : System Configuration

Category : Drive mechanism design
May14, 2010

System configuration is discussed based on the single axis motor driven mechanism shown on [Photo 3] in Tutorial #040.

(1) System configuration explained

[Fig.1] is a system configuration of the mechanism composed of three sensors (home sensor and two overrun prevention sensors), motor, ballscrew, and linear guides, explained in tutorial #040.


Programs containing linear speed, distance, direction, etc are stored in the programmable logic controller (PLC). The motion controller converts the programs into motor control pulses and sent to the stepper motor via the motor driver. This is an open loop system since the system does not have a function to compensate for errors based on motor movement results.

(2) Increased system reliability

(1) Use of overrun prevention sensors

If the overrun sensor malfunctions, the table may collide with the ballscrew support unit and damage and loss accuracy may occur. Sensor reliability is of high importance in order to prevent any possible collision caused damages to the system. These sensors are wired as N/C (normally closed), same logic as emergency stop switches.

(2) Prevention of environmental electrical noise intrusion

Programmed pulse outputs may be negatively affected by electrical noises from surrounding environment. It is best to dedicate a separate power line for the system to isolate from noises and voltage fluctuations. If not possible to do so, avoid connecting electrically noisy equipment to the same power line as the system. Use twisted pair wiring for all pulse signal connections. Use cable shielding scheme if needed.

Note: Examples of noisy equipment
* Large dryer furnace, spot welder, laser oscillator - - - Do not connect to the same power line or place near equipment that switches at high current ratings