Safety device

Abstract

A safety device includes a safety module ( 11 ), a data bus ( 12 ) and one or several transmitters ( 15, 16, 17, 18, 19, 20 ). The safety module transmits a pulse train (one dynamic signal) over the bus ( 12 ) constituting a loop, whereby the pulse train is connected to each of the transmitters, wherein the pulse is phase inverted.

1 . A safety device comprising a safety module ( 11 ), a data bus ( 12 ) and a number of transmitters ( 15 ,  16 ,  17 ,  18 ,  19 ,  20 ),  
       characterised in 
 that said safety module is arranged to. transmit a pulse train (a dynamic signal) over said bus ( 12 ) forming a loop, whereby the pulse train is connected to each of said sensors, in which the pulse is phase inverted and that the safety module ( 11 ) controls that said pulse from the detectors is time delayed.  
 
     
     
         2 . Device as claimed in  claim 1 ,  
       characterised in 
 that said transmitters comprise one or several of a sensor ( 13 ), an inversed switch ( 14 ), terminal strips, sensor mats, bumpers ( 15 ), light transmitters/-receivers ( 16 / 17 / 18 ), light curtains ( 19 ) and emergency shutdown button ( 20 ).  
 
     
     
         3 . Device as claimed in any of the claims  1  or  2 ,  
       characterised in 
 that the device may further be provided with one or several of automatically or manually monitored resetting, double safety outputs, information output for restoration indication, and output for status information to a PLC (Programmable Logic Controller).  
 
     
     
         4 . Device as claimed in  claim 1 ,  
       characterised in 
 that the signal sent out from the safety module is time delayed in relation to the signal coming back.  
 
     
     
         5 . Device as claimed in  claim 4 ,  
       characterised in 
 that the time delay varies with the number of transmitters coupled, whereby further control of that the correct number of transmitters is obtained.  
 
     
     
         6 . Device as claimed in  claim 1 ,  
       characterised in 
 that said transmitted pulse train is compared to the received pulse train, whereby a control of the time delay and the frequency is made by the safety module.  
 
     
     
         7 . Device as claimed in  claim 6 ,  
       characterised in 
 that if the signal is correct the safety outputs are kept closed, and the safety outputs are opened when a error or stop signal is received from one or several of the transmitters.  
 
     
     
         8 . A method at a safety device comprising a safety module ( 11 ), a data bus ( 12 ) and a number of sensors ( 15 ,  16 ,  17 ,  18 ,  19 ,  20 ),  
       characterised In 
 that said safety module sends a pulse train (a dynamic signal) over said bus ( 12 ) constituting a loop, whereby the pulse train is connected to each of said transmitters, in which the pulse phase is inverted, and that the transmitted pulse train is compared to a received pulse train, whereby the control of a time delay and the frequency is done by the safety module.