Omron CP - PROGRAMMING MANUAL 05-2007 Programming Manual page 679

Data Control Instructions
Description
Note
646
Area
Indirect DM addresses
in BCD
Constants
Data Registers
Index Registers
Indirect addressing
using Index Registers
Receives a duty ratio or manipulated variable input from the word address
specified by S, converts the duty ratio to a time-proportional output (see note)
based on the parameters specified in words C to C+3, and outputs a pulse
output to the bit specified by R.
A time-proportional output is changed proportionally based on the ON/OFF
ratio in input word S. The period in which the ON and OFF status changes is
known as the control period and is set in parameter word C+1.
Example: When the control period is 1 s and the input value is 50%, the bit is
ON for 0.5 s and OFF for 0.5 s. When the control period is 1 s and the input
value is 80%, the bit is ON for 0.8 s and OFF for 0.2 s.
Generally, TPO(685) is used together with PID(190) or PIDAT(191) and the
PID instruction's manipulated variable result word (D) is specified as the input
word (S) for the TPO(685) instruction. Also, an output bit allocated to a Tran-
sistor Output Unit is generally specified as R and a solid state relay is con-
nected to the Transistor Output Unit to perform time-proportional control of a
heater (proportional control of the ON/OFF ratio).
Combining TPO(685) with a PID Control Instruction
When combining TPO(685) with a PID control instruction, the manipulated
variable input is divided by the manipulated variable range to calculate the
duty ratio, that duty ratio is converted to a time-proportional output, and pulses
are output.
0.00
PID
S
PV input
C
PID parameters
D0
Manipulated
variable
TPO
D0
MV
C
Parameters
R
Pulse output
S
*D0 to *D32767
#0000 to #FFFF ---
(binary)
DR0 to DR15 ---
---
,IR0 to ,IR15
–2048 to +2047 ,IR0 to –2048 to +2047 ,IR15
DR0 to DR15, IR0 to IR15
,IR0+(++) to ,IR15+(++)
,–(– –)IR0 to, –(– –)IR15
PID calculation
Manipulated variable (MV)
MV
D0
MV MV range
Duty ratio (0.00% to 100.00%)
Conversion to time-proportional
output
Section 3-17
C R
---
---
---
Output range
= MV range