PCC-IV Instruction Manual (rev. 0.2)
Page 5-2
Section 5 – Configuring Blockware
Blockware Basics
PCC-IV uses blockware to implement the control strategies that are contained in the memory of the PCC-IV. The
word blockware is derived from the words Block diagram and software. The use of blockware results in a clearly
documented, easy to understand, and easy to configure a system. The basic elements of blockware are as follows:
Blocks
The PCC-IV memory has 256 Blocks (B0 – B255). Each block is a container into which a blockware function is
placed. Think of a block as a cell in an Excel or similar spreadsheet; you put a formula or a function into a cell, and
the formula uses the values from other cells as inputs for the formulas. Another analogy would be physical relay
sockets that have signal processing modules plugged into each socket (i.e., Block). The controller includes sufficient
memory to handle 256 Blocks (see below).
Library of Functions
The PCC-IV has an extensive library of functions to handle almost any type of control task. These functions are
identified and described in detail in Section 6 of this manual. The library includes functions for the conversion of
inputs to engineering values, mathematical operations, logical operations, timing operations, the traditional PID
algorithm and other types of special
PID
functions, and many others. Additional special functions such as “Learn”,
“Boiler Efficiency”, etc. are included and are described, in depth, in Section 6.
Any-Function-Any-Block
Each block is assigned a function type during configuration. Any function type can be used in any block number.
The block number only determines the order in which the blocks are calculated. In the example below at left, block
number 22 is not being used, so it has the default
NOP
, or “
N
o
OP
eration” function in it. At right, Block 22 was
changed from a
NOP
to a
HIALM
(high alarm) function type.
Reusable Functions
Almost all PCC-IV function types can be used as many times as required, within the 265 Block limit. There are some
functions that are directly linked to the hardware that can only be used as many times as there is mating hardware.
For example, only one
PANEL
function (front panel display interface) can be used because there is only one front
panel. While those related to
PID
functions, curve fitting functions, etc. can be used as many times as is deemed
necessary for the application.
Softwiring
Most function types, like
HIALM,
need information from other sources (i.e., blocks) to calculate a result. Softwiring
is the term used to describe how the blocks are interconnected within the software. Softwiring allows the Input of a
Block to monitor the Output of any other block. At right below, the PV (Process Variable) input of block 22 (
HIALM
)
is monitoring the output of Block 20 (
AIN
), via a softwiring connection.
Note:
If a block input is not softwired to some other signal, a value of 0 is used to calculate the function for that
input (for analog inputs: 0 = 0.00%, for discrete inputs: 0 = False).
