Omron SYSMAC CJ - REFERENCE MANUAL 08-2008 Reference Manual page 829

Data Control Instructions
Description
Area
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.
Note 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.
000000
In this case, set the same value for the PID Control instruction's output range
and the TPO(685) instruction's manipulated variable range. For example,
when the PID Control instruction's output range and the TPO(685) instruc-
tion's manipulated variable range are both set to 12 bits (0000 to 0FFF hex),
the duty ratio is calculated by dividing the manipulated variable from the PID
Control instruction by 0FFF hex and TPO(685) converts that duty ratio to a
time-proportional output.
S
---
,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
S
PV input
PID calculation
C
PID parameters
D00000
Manipulated
D00000
variable
TPO
D00000
MV
C
Parameters MV
R
Pulse output
Duty ratio (0.00% to 100.00%)
Conversion to time-proportional
output
Section 3-18
C R
Manipulated variable (MV)
MV
Output range
= MV range
MV range
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