Samson foundation 3787, Mounting And Operating Instructions, Page: 78 / 96

7.5 Other parameters
7.5.1 Stale counter
The stale counter is used to assess the "quality" of a process variable received via a cyclically
configured link (publisher subscriber link).
The process variables that are "connected" among various function blocks are transferred
using these links.
For this purpose, the preceding block (Publisher) sends the process variable on the bus at a
defined point in time. The successive block(s) (subscriber) "listen" at this point in time on the
bus. The receiving blocks check whether there is a valid value at the configured point in time.
A value is valid when it has the status "Good" at the expected point in time.
The stale counter defines how many successive stale (bad) values are accepted until the fault
state mechanism of the block is enabled.
When the stale counter is set to "0", this monitoring function is cleared.
7.5.2 Link objects
Link objects are used to link Function Block inputs and outputs (configurable cyclic links).
22 link objects can be configured for each positioner.
7.5.3 LAS capabilities
The number of projectable links and schedules is matched to the requirements and possi-
bilities in the DeltaV System from FISHER-ROSEMOUNT.
Functioning as LAS the positioner can support the following:
1 schedule
1 subschedule
25 sequences per subschedule
25 elements per sequence
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EB 8383-1 EN
Parameter description