Siemens Simatic S7 Series System Manual

PID loops and tuning
11.1 PID loop definition table
S7-200 SMART
470 System Manual, 09/2015, A5E03822230-AC
Table 11- 2 Expanded description of control and status fields
Field
Description
AT Control (ACNTL)
Input - Byte
EN
Set to 1 to start auto-tune; set to 0 to abort auto-tune
AT Status (ASTAT)
Output - Byte
W0 Warning: The deviation setting is not four times greater than the hysteresis set-
ting.
W1 Warning: Inconsistent process deviations may result in incorrect adjustment of the
output step value.
W2 Warning: Actual average deviation is not four times greater than the hysteresis
setting.
AH Auto-hysteresis calculation in progress:
0 - not in progress
1 - in progress
IP Auto-tune in progress:
0 - not in progress
1 - in progress
Each time an auto-tune sequence is started the CPU clears the warning bits and sets the in
progress bit. Upon completion of auto-tune, the CPU clears the in progress bit.
AT Result (ARES)
Input/Output - Byte
① Result code
D Done bit:
0 - auto-tune not complete
1 - auto-tune complete
Must be set to 0 before auto-tune can start
Result
Code
00 - completed normally (suggested tuning values available)
01 - aborted by the user
02 - aborted, watchdog timed out waiting for a zero crossing
03 - aborted, process (PV) out-of-range
04 - aborted, maximum hysteresis value exceeded
05 - aborted, illegal configuration value detected
06 - aborted, numeric error detected
07 - aborted, PID instruction executed without having power flow (loop in manual
mode)
08 - aborted, auto-tuning allowed only for P, PI, PD, or PID loops
09 to 7F - reserved

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.