Configuration of Function Blocks
Section
3-1
79
Note 2
All analog signals on the Loop Control Unit are processed (input or output) in
% units. (They are not processed in engineering units.) Though the data
range varies according to each ITEM, the maximum range is -320.00 to
+320.00%. For example, the data range for PV or Set Point in Control blocks
such as the PID block is -15.00 to +115.00%, and the data range for MV is -
320.00 to +320.00%. When analog signals are connected, data is handled
with "%" as the common unit regardless of differences in the data ranges
between ITEMs. (Note, however, that minus values are regarded as 0.00%
when entered to ITEMs whose data range starts from 0.00%.)
The following three processes are required for displaying or setting in
engineering units:
1) Use CX-Process Tool to specify function blocks such as Control blocks or
analog signals (including parameters) and contact signals (including
parameters) to be monitored by CX-Process Monitor as the source
designation in the Block Send Terminal to Computer blocks.
2) Use CX-Process Tool to set the tag numbers for function blocks or
analog signals (including parameters) and contact signals (including
parameters), and set the high and low limit scaling and unit. (A default
fixed name "tag ITEM" is already allocated to each of the ITEMs in the
function blocks.)
3) Use CX-Process Monitor to select the tag ITEM or tag number that was
selected in CX-Process Tool above, and display or set each ITEM (for
example, Set Point or PV) in the function blocks or the analog signals
(including parameters) and contact signals (including parameters) in
engineering units.
ITEMs in the Step Ladder Program block
The table below shows the content of the 100 ITEMs ITEM011 to ITEM110 in
the case of the Step Ladder Program block (Block Model 301).
ITEM type
Block diagram symbol
Description
Setting method
Sequence
command
CCBBII
Sequence command
CCBBII
CCBBII
Note: CC: Command code,
BB: Block address,
II: ITEM No.
ITEM011 to ITEM110 correspond
to individual commands.
A single command (e.g. LOAD,
OUT) is described to a single ITEM,
and the block address and ITEM
number of the specified input
source and output destination are
described as operands.
Commands are described using
command codes 01 to 30 (e.g.
LOAD is 01 and OUT is 07).
Describe
commands to
ITEM011 to
ITEM110 of the
Step Ladder
Program block
(Block Model
301).
Example of a single command
ITEM
Command code (command)
Operand
011
01 (LOAD)
001 013 (block address, ITEM No.)
Block address: 001
ITEM number: 013
Command: LOAD (code 01)