Library of Function Blocks
4.15
CHST - RESTART CONDITION
CHST configure the operating mode of the respective loop after a power interruption.
CLIM-OUTPUT LIMITER ONLY ON AUTOMATIC
The output limiter actuates normally in both operating modes: manual and automatic. CLIM allows the
limiter to actuate only on the automatic mode.
EXAMPLES:
1) As an emergency situation defined by a high logic level signal, the control output shall remain in the
last value prior to the emergency, unless the operator decides to change it. If the emergency situation
disappear, the control shall remain in manual mode.
Solution: This is a "Forced Manual" situation. The emergency signal shall be linked to input D and
the following parameters shall be configured:
CST1 = 0 → CH1 goes to or remains in position "1" (Manual) whenever an emergency situation
occurs.
CCH1 = 3 → Input D signal switches CH1.
CSA1 = → any value.
CLMV = 0 → The keys < > and < > shall operate.
CLAM = 1→ Locks the <A/M> key, thus preventing CH1 to be switched to position "0", allowing return
in Automatic mode.
In the same emergency situation described above, the output signal shall go to 2%, remaining in this
value throughout the emergency situation. When the emergency signal disappear, the controller
shall remain in manual mode.
Solution: This is a "Safety Output" situation. The emergency signal shall be linked to Input C, the
value 2% (from an adjustment block or a constant value block) shall be linked to Input B
and the following parameters shall be configured:
CST1 = 1 → CH1 goes to or remains in position "0" (Auto). The output will be the input B value in the
instant of CH3 switching.
CCH1 = 4 → Input C signal switches CH1.
CSA1 = 1 → Controller shall remain in Manual after the emergency signal drops.
CLMV = 2 → The keys < > and < > are locked as long as the emergency signal is present.
CLAM = 2 → CH1 is locked since the emergency signal is present.
TYPE MNEM DESCRIPTION RANGE DEFAULT
I LIA Input A (Automatic) 0
I LIB Input B (Safety) 0
I LIC Input C (Safety Switch) 0
I LID Input D (Forced Manual)
Addresses
0 to 170 / 225 to 240
0
I CST1
CH1 position when inputs C or D have a high
logic level and parameter CCH1 ? 0, 1 or 2
0 - Position 1 (Manual Position in
normal operation)
1 - Position 0 (Automatic Position in
normal operation)
0
I CCH1 Actuation of CH1
0 - <A/M> Key
1 - Locks in Position 0 (AUTO)
2 - Locks in Position 1 (MANUAL)
3 - <A/M> Key or Input D
4 - <A/M> Key or Input C
5 - <A/M> Key or Inputs C or D
0
I CSA1
CH1 position when input C returns to a low logic
level
0 - Last Position
1 - Position 1 - (MANUAL)
2 - Position 0 - (AUTO)
0
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