delay from encoder to output on Siemens S7-1500F

[Mechamania]

Hi
I need a safety system with safety encoders as input (profisafe bus) and digital outputs. When position or speed of some rotating device exceeds some numbers, the safety system should enable some brakes. My plan is to use a Siemens S7-1500F safety PLC.
What would the estimated delay be from encoder turning to digital output?

 

[widelto]

Some high speed boards have outputs independent from plc outputs so enabling an output can be inmediate. At least this happens with allen bradley, do not know if siemens has the same capabilities.

 

[mk42]

Many Siemens drives have this capability built in. Look into Safe Brake Control (SBC) And Safe Limited Speed (SLS).

If you google "Profisafe encoder" you'll find a number of companies that sell them.

How fast do you need it to be? Any safety system needs to start from a risk assessment that lists what the hazard is, and what reaction time is needed to guarantee safe operation.

The cycle time of the safety program is adjustable, as is the IO update rate. You COULD have a 1ms safety scan, and 1ms communication to the encoder and safety output, for a 3ms delay. You could possibly do it faster, although the actual actuator will take so much longer to work that it isn't needed. Most safety programs I see target an input to output reaction time of between 100-150ms.