Function Blocks; Loop Function Block Types - Siemens 353 User Manual

Introduction
Often in this publication, reference is made to the labels on the controller to ensure that the controller being installed
has the correct power input, I/O, communication options, and approvals. This is particularly important when non-
incendive requirements are present or a critical process is involved where a custom configuration or calibration has
been created. Label locations are shown in Figure 1-1 and typical labels are shown in Section 13 Model Designation
and Specifications.

1.2 FUNCTION BLOCKS

Controller software is built on proven function block designs from previous controller products. In many cases, the
controller has been enhanced with features only now possible with state of the art technology.
Function blocks are selected for use within a LOOP. Multiple loops can be configured, and each loop can be
associated with an operator faceplate. Certain blocks are used once within each loop (e.g. controller, setpoint,
auto/manual), others can be used as many times as needed. Some notable features include Auto Tuning within the
PID function blocks, an expandable Sequencer that allows configuration of up to 250 steps, and up to 256 discrete
inputs and outputs. In addition, the Graphical Configuration Utility, i|config, can be used to design the logic in a
ladder diagram. Combining these features with continuous control loops within the same controller offers a well-
integrated solution for small batch operations.
Several function blocks are available at the station level for configuration of STATION level parameters, such as
the station address and station tag name. Function blocks include the CLOCK block and the ETHERNET block to
configure parameters such as the IP address. All other function blocks are used for configuration within an
individual LOOP. Control implementations are configured in the Siemens 353 by first creating a loop, then entering
a unique loop tag name and selecting function blocks for use within that loop. A number of loops can be configured
in the Siemens 353 and a number of function block types are available as described in the sections that follow.

1.2.1 LOOP Function Block Types

Local I/O Function Blocks are provided on both the MPU Controller Board
and the I/O Expander Board. These blocks can be used in any LOOP, but as
fixed resources are expendable. When used within a loop, the unique block
name becomes <loop>.<block> (e.g. TC2053.AIN1 for Analog Input 1 used in
loop TC2053).
Fixed Loop Function Blocks can be selected once for use within each
configured LOOP. The operator display function block (e.g. ODC
Operator Display for Controllers) defines the loop type, the function of the
local faceplate, as well as the processing of commands coming from a
remote workstation. A single controller function block can be selected
from one of five available choices (ID, ON_OFF, PD, PIDAG, and PID)
within each loop. When used within a loop the unique block name
becomes <loop>.<block> (e.g. TC2053.PID for the PID controller used in loop TC2053).
Arithmetic Function Blocks are also designated as LOOP function blocks
and can be used as many times as needed in each loop. Each use of a block is
automatically assigned a unique name (i.e. MATH01, MATH02) within each
loop so that the unique block name becomes <loop>.<block> (e.g.
TC2053.MATH01).
Logic Function Blocks are also designated as LOOP function blocks and
can be used as many times as needed in each loop. Each use of a block is
automatically assigned a unique name (i.e. AND01, AND02) within each
loop so that the unique block name becomes <loop>.<block> (e.g.
TC2053.AND01).
1-4
AIN_
AIN_+
ANALOG INPUT
AIN_c EXTRACTOR
ESN = 000
PID
R
Range
O1
P
Process
PID
AE
S
Setpoint CONTROLLER
F
Feedback
AW
A
Auto
I
Initialize
MTH_ ESN = 000
Input A A
MATH
Input B B
ADD, SUB, MUL, DIV
C
Input C
AND_ ESN = 000
Input A
A
AND
Input B B
C
Input C
UM353-1B
Output 1
O1
Quality Status
QS
Output
Absolute Error
AT Warning
O1
Output 1
O1
Output 1
April 2012