The function package "Initiation" is only available for Safety Light Curtains with 14 mm and 30 mm resolution. Beginning with firmware version 3.10, it offers the following options in addition to the standard functions:
- Controlling safely a machine with the receiver (cycle control)
- Defining beam zones with fixed and floating blanking
- Defining beam zones with reduced resolution
- Bypassing the safety output for a limited time
Application example
Problem:
Various workpieces are fed into a small hydraulic press. Depending on the workpiece, an operator changes the operating mode of the press.
Operating mode 1: Thin sheets that protrude out beyond the protective field of the machine are processed. The Safety Light Curtain works in Guard operation with restart interlock and 1-beam reduced resolution. The safety distance is perma-nently set to the effective resolution that can be achieved in this arrangement.
Operating mode 2: Heavy compact workpieces are processed. They are removed from the machine by the operator after they have been processed. Then the next workpiece is inserted for processing. The Safety Light Curtain works in double-break operation to save the start button from being pressed frequently by the operator. This increases productivity. Since the workpiece is unusable if it is inserted in the wrong position during the pressing operation, the pressing operation must not be started until the workpiece is in the correct position. To further increase productivity, the bypass function is activated in cycle operation during the upward motion of the press. A sensor in the upper reverse point generates the clear signal to delete the cycle counter. A flashing pilot light indicates locally the number of cycle interventions remaining.
Monitoring of the control valves will be implemented by the Safety Light Curtain with a feedback circuit. The status of the OSSDs will be reported to a PLC.
Solution:
The Basic I/O Configuration of the Safety Light Curtain with the function package"Initiation" is set to "2 operating modes (external, freely selectable), Bypass". Because of this, a changeover switch is expected on L4 for the operating mode, while the two bypass sensors, that are simultaneously activated within 200 ms < t < 500 ms, are connected to L1 and L2. The sensors are activated just before they run through the lower reverse point and are deactivated before they reach the upper reverse point. To save money, the clear signal is derived from the negative signal edge of a bypass sensor instead of being generated by another sensor. A 1-beam reduced resolution is set in the protective field. Reduced resolution is only in effect in Guard operation while the system switches back to full physical resolution during the changeover to double-break operation in the receiver. An enable signal is expected on L3 that enables the last cycle and thus ensures that the press is only turned on if the workpiece is in the correct position. Internal Start/Restart Interlock and External Device Monitoring are activated. The start button and pilot light must be connected to L5, the valve feedback circuit to M2. M3 returns the OSSD state to a PLC.
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