SSP North AB
30/08/2018
Manual V2f
88
13.10.5.3 Best Practices
For the best safety communication response times, it is crucial that safety signals only go over radio
once. Using a global memory from another node in logic and sending the result on a new memory
effectively doubles the reaction time added from radio, as the memory must go via the radio twice.
13.10.5.4 Controlling outputs directly via radio or CAN
When using any type of communication, the idea that loss and return of communication must not
result in dangerous function must be applied to all simplifier safety systems. When a hold to run device
is controlling a safety output directly using a Global or a CAN memory it is crucial to enable the start-
up function for the memory. This way one have to release and activate the hold to run device in case
of communication or power failure in the Safety Simplifier which uses the memory.
For other safety devices it is not recommended to use the start-up memory for the same action. In
case a stop is initiated from communication or power failure in the Safety Simplifier unit controlling a
machine function a new start is normally required. This can easily be done by using a reset function in
that unit and to have start(reset) buttons in any of or in all the Safety Simplifier units. To give a new
start is common requirement after communication or power failure.
Illustration 13.44: Driving a relay output in node 2 directly using a global memory
from node 1.
Illustration 15.64: Driving a relay output in node 2 via a reset block using a global
memory from node 1.
