Siemens Simatic S7 Series System Manual

PID loops and tuning
11.1 PID loop definition table
S7-200 SMART
System Manual, 09/2015, A5E03822230-AC
469
Offset
Field
Format
Type
Description
48 Hysteresis (HYS) REAL In Normalized value of the PV hysteresis used to deter-
mine zero crossings (range: 0.005 to 0.1). If the ratio of
DEV to HYS is less than 4, a warning will be indicated
during auto-tune.
52 Initial Output Step
(STEP)
REAL In Normalized size of the step change in the output value
used to induce oscillations in the PV (range: 0.05 to
0.4).
56 Watchdog Time (WDOG) REAL In Maximum time allowed between zero crossings in sec-
onds (range: 60 to 7200).
60 Suggested Gain (AT_K
C
) REAL Out Suggested loop gain as determined by the auto-tune
process.
64 Suggested Integral Time
(AT_T
I
)
REAL Out Suggested integral time as determined by the auto-tune
process.
68 Suggested Derivative
Time (AT_T
D
)
REAL Out Suggested derivative time as determined by the auto-
tune process.
72 Actual Step size
(ASTEP)
REAL Out Normalized output step size value as determined by the
auto-tune process.
76 Actual Hysteresis
(AHYS)
REAL Out Normalized PV hysteresis value as determined by the
auto-tune process.

Siemens Simatic S7 Series Specifications

General

CPU	Varies by model (e.g., S7-300, S7-400, S7-1200, S7-1500)
Communication Interfaces	PROFIBUS, PROFINET, Ethernet, MPI
Programming	TIA Portal, STEP 7
Programming Languages	LAD, FBD, STL, SCL, GRAPH
I/O Modules	Digital, Analog, Specialty modules available
Operating Temperature	0°C to 60°C (standard models)
Mounting	DIN rail mounting
Operating Voltage	24V DC or 120/230V AC (varies by model)
Protection Class	IP20 (standard models)
Memory	Varies depending on the S7 model. Includes work memory (RAM) for program execution, load memory (EEPROM or Flash) for program storage, and system memory for operating system functions. Memory sizes range from kilobytes to megabytes.