Festo SFC-LAC CO Series, Manual, Page: 202 / 328

B. Parametrizing in accordance with FHPP−FPC
B−8
Festo P.BE−SFC−LAC−CO−EN en 0708NH
B.1.3 Rules for task−reply processing
Rules Description
1 If the master sends the identifier for No task", the SFC−LAC will reply with the response
identifier for No reply".
2 A task or reply telegram always refers to a single parameter.
3 The master must continue to send a task until it receives the appropriate reply from the
SFC−LAC.
4 The master recognizes the reply to the task placed:
by evaluating the reply identifier,
by evaluating the parameter number (PNU),
if applicable, by evaluating the subindex (IND),
if applicable, by evaluating the parameter value.
5 The SFC−LAC provides the reply until the master sends a new task.
6 a) A write task, even with cyclic repetition of the same task, will only be carried out once
by the SFC−LAC.
b) Between two consecutive tasks with the same task identifier (AK), parameter number
(PNU) and subindex (IND), the task identifier 0 (no task) must be sent and the reply
identifier 0 (no reply) must be awaited. This is to ensure that an old" reply is not
interpreted as a new" reply.
Tab.B/6: Rules for task−reply processing