Weidmuller WI-I/O-9-U2: Wireless Mesh I/O & Gateway User Manual V1.2.2 - Manual (Page 68)

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In Figure 51 - Failsafe Block Digital
’ above, register 40501 holds an analog value that
has been mapped from another module and is updated every 60 seconds.
The configuration is configured so that on start-up the module will write a value of 16384
into register 4
0501 and then start counting down the “Fail Timeout” period , in this case
it is 130 seconds which is a little over two times the update period from the sending
module .
If after 130 seconds, the module still has not received an update from the other module,
register 4
0501 will be set to the “Fail Value” (in this case 0).
If the “Invalidate on Fail” were ticked, the value would be set to a null or invalidated
value (~).
If this register happens to be mapped to another module and the state is ‘Invalidated’
the mapping would be inhibited until the” Invalid” value was updated with a real value.
The maximum number of Fail Safe blocks you can have is 50.
In Figure 50- Failsafe Block Analog ” shows Digital Outputs 1-8 will be initialised on
startup
(turned on) and then start the ‘Fail Timeout’ countdown from 60 seconds after
which time the outputs will be set to the fail value (off) unless the output is updated.
“Invalid” register state
Figure 51- Invalid Register State
All registers within the module can have various states depending on what type of
register it is and what sort of value it holds, a typical analog range is between 0 and
65535 and a digital can be 0 or 1.
All registers that are not associated with any physical I/O have another state which we
call “invalid”, this state means that the value has not been written to and so does not
hold a value but more a non-value or null.
If you were to read the registers using the “I/O Diagnostics” an invalid register would
read “~“ as shown in Figure 51 above.
Any mapping with an invalid register will be inhibited from sending. This
is to ensure the data that gets to the destination is valid and not just
default values that the module starts up with. Refer to section 4.3.11