Yaskawa Remote I/O Controller LAN Node PCB for use with Microtrac DSD LAN - Manual (Page 4)

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drive that has allocated an output has an
output timer in the RIO. A drive’s output
timer is reset to the original output time
each time that an output update message is
received by the RIO from the drive through
the LAN. When a drive’s output timer times
out, the RIO assumes that communication
with the drive is no longer occuring; thus all
of the outputs that the drive has allocated
will be driven to 0.
Furthermore, when specifying an
output, a fault reaction must be defined. A
fault reaction may be defined as either
Allocate or Deallocate. If a drive’s output
timer times out, the fault reaction
determines what the RIO should do. If
defined as Allocate, then the output will
remain allocated to the drive. If defined as
Deallocate, then the output will no longer be
allocated to the drive. Consider the
following case:
A drive sees that an RIO is powered
up (by the RIO announcing that it is
powered up). The drive then sends a
message to allocate an output with a
given output time and a fault reaction.
The drive then proceeds to send output
update messages to update the allocated
output, at time intervals which are
less than the given output time. For
some unforseen reason, the drive does
not send the RIO an update message
within the given output time. Some
time later, the drive resumes sending
the RIO output update messages.
In this case, when the output timer
timed out, the output would have been
driven to 0. When the drive resumes
sending the RIO output update messages,
the RIO will react differently depending on
how the fault reaction was defined. Had
Allocate been defined as the fault reaction,
then the output value would have been set
to the value in the message. Had Deallocate
been defined as the fault reaction, then the
output update messages received from the
drive, after the fault, would be ignored (since
the output is no longer allocated to the
drive). Deallocate would require the drive to
allocate the output again, which would
mean resetting the drive or power cycling
the RIO.
NUMERIC INPUTS
Numeric inputs are any numeric type
inputs such as analog inputs and
Thumbwheel switch inputs. Any Drive
connected to the LAN may request to be
updated with the value of the input. The
way that the RIO keeps the drive updated
depends on the type of numeric input and is
described in the following text.
Numeric Inputs From A/D Sources
Many A/D conversions are made on
each analog input in each second. Due to
the nature of analog signals (they may have
many minor fluctuations), the drive will not
be updated every time that the A/D
conversion yields a different result than the
previous conversion. This would tend to tie
up the LAN with unnecessary messages.
Instead, numeric update messages are sent
to all concerned drives at regular intervals
(approximately 140 ms per interval).
The value sent is the average of all of
the A/D conversions made since the last
numeric update message. The value sent is
in a floating point format and will range
from -1 to +1, corresponding to -maximum
analog input value to +maximum analog
input value, respectively.
When specifying a Numeric input, a
decimal point location value must be
defined. This value is ignored when the
Numeric input is from an A/D source.
Numeric Inputs From Thumbwheel Switch
Sources
Any time a Thumbwheel Switch
Bank’s Push-To-Load input is asserted, the
value set on the Thumbwheel Switch Bank
is read. If at this time the value is different
from the previous value, then a numeric
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