YOKOGAWA ADMAG TI Series

<5. Functions>
71
IM 01E21A02-03EN
5.3 Limit Switch Function
5.3.1 Limit Switch
The limit switch function is to transmit 0 and 1 as a parameter by judging whether the selected
processvalueisaboveorbelowthethresholdvalue.Thefunctionoperatesasthegurebelow.
State 1
State 0
F0447.ai
Active direction: Low limit
Set point + Hysteresis
Set point
Output
Process value
Time
Active direction: High limit
Set point
Set point - Hysteresis
Output
Process value
Time
State 1
State 0
Figure 5.3.1 Limit Switch Operational Schematic Figure
Function item Description of Parameter
Operation
direction
Speciestheoperationdirectionofthelimitswitch.
0 Low limit
1 High limit
Threshold Speciesthethresholdforjudgment.
Hysteresis Speciesthehysteresis(onlyapositivevaluecanbespecied).
Contact point
output
0(State0)or1(State1)isentered.
Figure 5.3.1 shows examples of the operation for a case where the operation direction is Low
limit on the left side and a case where the operation direction is High limit on the right side.
WhentheoperationdirectionisLowlimit,acontactpointoutputbecomes1(State1)ifthe
process value goes below the threshold. When the process value goes over the value obtained
byaddingthehysteresistothethreshold(threshold+hysteresis)afterthat,thecontactpoint
output becomes 0.
When the operation direction is High limit, the operation is opposite to the operation for Low
limit.Whenprocessvaluegoesoverthethreshold,thecontactpointoutputbecomes1(State
1).Whentheprocessvaluegoesbelowthevalueobtainedbydeductingthethresholdfromthe
hysteresis(threshold-hysteresis),thecontactpointoutputbecomes0.
On this product, two units of the above parameter and process value unit are prepared for each
process value. Meanwhile, the value of contact point output is updated only when selected by the
channel of the DI function block.
 Flow velocity limit switch
Display --
F
OUNDATION
Fieldbus
DeviceConguration►STB►DeviceConguration►Conguration►LimitStsVelocity
►(seebelow)
Block
Name
Relative
Index
Parameter
Description
Display F
OUNDATION Fieldbus
STB
108
--
LimitStsVelocity1Value►
Lmt Sts Velo1.Status
Displays the status of the contact point
outputofowvelocitylimitswitch1.
STB --
LimitStsVelocity1Value►
Lmt Sts Velo1.Value
Displaysthecontactpointoutputofow
velocity limit switch 1.