Yokogawa YVP110 - Manual (Page 37)

<5. Setup>
5-4
IM 21B04C01-01E
5.4 Checking Valve Actions
After carrying out auto tuning, check step
responses by changing the value of the transducer
block's final valve position setpoint, FINAL_VALUE.
value. Also, check whether the valve acts correctly
over the 0-100% position range.
NOTE
Only when the target mode is in MODE_BLK
parameters in both the AO and transducer blocks
are O/S, can FINAL_VALUE.value be written.
It is not usually necessary to readjust the control
parameters after auto tuning. However, when
using the Double Acting Type or if the expected
response characteristics cannot be obtained
using auto tuning, either conduct manual tuning
in reference to APPENDIX 6 or refer to Section
18.5 Troubleshooting Auto Tuning.
5.5 Setting Parameters of
Transducer Block
Set the following parameters as necessary. For the
settings made as default when shipped, see the
parameter lists in Appendix 1.
(1) Position-to-flow Rate Characteristic Type
The parameter POSITION_CHAR_TYPE
defines the characteristics between the valve
position and flow rate, and is set to linear by
default. Write the appropriate value:
1 = linear
2 = equal percent (50:1)
3 = equal percent (30:1)
4 = quick open (reversal of equal % - 50:1)
5 = Camflex Percentage
255 = user-defined
Writing the value 255 allows you to define the
desired characteristics by 10 line segments for
evenly divided input levels. The coordinates
(0,0) and (100,100) are fixed; set the values
corresponding to OUT(Output of AO block) =
10%, 20%, 30%..., 80%, 90%. Note that a set
value must be greater than the preceding set
value; the output must increase as the input
increases.
F0502.ai
(1) (4)
0
Output(OUT) of AO block
Valve position
(3)
(2)
(5)
(1) Linear
(2) Equal % (50 : 1)
(3) Equal % (30 : 1)
(4) Quick Open
(5) Camflex Percentage
Figure 5.2 Position-to-flow Rate Characteristic
Type
(2) Final-value Limits
Eu_100 and Eu_0 in the parameter FINAL_
VALUE_RANGE define the upper and lower
limits of FINAL_VALUE.value of the transducer
block.
CAUTION
Even if the range of FINAL_VALUE.value is
limited by FINAL_VALUE_RANGE, the actual
valve position is set to outside the FINAL_
VALUE_RANGE setting when the tight-shut or
full-open action described below is activated.
(3) Tight-shut and Full-open Actions
The tight-shut action is an action to decrease
the output pressure to a level much lower than
the 0% pressure level (or to increase it much
higher than the 0% pressure level for an air-
to-close valve) when FINAL_VALUE.value
is less than FINAL_VALUE_CUTOFF_LO in
order to ensure that the valve is tightly shut
off. Conversely, the full-open action is an
action to increase the output pressure to a level
much higher than the 100% pressure level (or
decrease it much lower than the 100% pressure
level for an air-to-close valve) when FINAL_
VALUE.value is larger than FINAL_VALUE_
CUTOFF_HI in order to ensure that the valve is
fully open.
A hysteresis of 1% is applied to the thresholds,
FINAL_VALUE_CUTOFF_LO and FINAL_
VALUE_CUTOFF_HI.