Samples For Fb 58 "Tcont_Cp" With Short Pulse Generator Sampling Time - Siemens SIMATIC Manual

Examples for the Temperature Controllers
6.3 Samples for FB 58 "TCONT_CP" with Short Pulse
Generator Sampling Time
The two samples described here are identical to the "pulse controller" sample
described in Section 6.2. The only differences are in the call mechanism as
described below.
The FB 58 "TCONT_CP" block contains a mechanism that allows the processing of
the controller stage with its intensive calculations and the tuning to be shifted to
OB1 or a slower cyclic interrupt OB (for example OB32: 1 s). You can use this
mechanism when your CPU has a heavy load and you require high accuracy and
therefore a reduction of CYCLE_P to CYCLE.
•
The "pulse controller OB35, OB1" sample is suitable for S7-300 since only one
cyclic interrupt level is available.
The following figures show the block call with a short pulse generator sampling
time on an S7-300:
OB1 (free cycle)
A
JCN
Call TCONT_CP, DB_TCONT_CP
M001: NOP 0
•
The "pulse controller OB35, OB32" sample is suitable for S7-400 since several
cyclic interrupt levels are available.
The following figures show the block call with a short pulse generator sampling
time on an S7-400:
OB32 (e.g. 1 s)
Call TCONT_CP, DB_TCONT_CP
6-6
"DB_TCONT_CP".QC_ACT
M001
...
SELECT = 1,
...
...
SELECT = 3,
...
OB35 ( e.g. 20 ms)
Call TCONT_CP, DB_TCONT_CP
...
SELECT = 2,
...
OB35 (e.g. 20 ms)
Call TCONT_CP, DB_TCONT_CP
...
SELECT = 2,
...
PID Temperature Control
A5E00125039-02