CST Timestamped Input Data
The module returns general fault and input data along with the value of the system clock
(from its local chassis) when the data changes. The system clock resides in the module, and
is synchronized with all of the other system clocks in the same chassis (when there is a CST
master in the chassis).
The timestamp samples the system clock after the data has been sampled and all filter
delays are completed.If Change of State is enabled for any input points, the timestamp
reflects the time when the module detected the change of state.
If the module detects more than one change of state before it manages to send the data out
(either because there are several input points with the change of state enabled, or because
the one point is changing rapidly), the timestamp is written into the buffer each time the
module detects a change of state. Thus, the timestamp reported to the controller reflects
the last enabled change of state that occurred before the data was transmitted.
buffer
1.) In software terms, a register or group of registers used for temporary storage of data, to compensate for transmission rate differences between the transmitter and receiving device. 2.) In hardware terms, an isolating circuit used to avoid the reaction of one circuit with another.
TIP:
On diagnostic inputs from a diagnostic output module, the timestamp reflects the time
that the module detected the fault, and if several faults occur in one message period, the
timestamp reflects the time the last one was detected.
The most effective way to use the CST system to coordinate outputs with inputs is to use
output and input modules residing in the same chassis and synchronized with the same CST
master. This makes it possible to schedule an output change of state up to 16 seconds after
an input change of state, simply by doing arithmetic on the low order bits of the CST
timestamps. The CST feature then performs the synchronization of outputs with inputs for you
with a high degree of precision.
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