Limit Switch Function; Limit Switch - YOKOGAWA Admag TI Series User Manual

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 figure below.
Active direction: Low limit
Set point + Hysteresis
Set point
State 1
Output
State 0
Figure 5.3.1 Limit Switch Operational Schematic Figure
Function item
Operation
direction
Threshold
Hysteresis
Contact point
output
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
Block Relative
Name Index
STB
108
STB
Process value
Specifies the operation direction of the limit switch.
0 Low limit
1 High limit
Specifies the threshold for judgment.
Specifies the hysteresis (only a positive value can be specified).
0 (State 0) or 1 (State 1) is entered.
--
Device Configuration ► STB ► Device Configuration ► Configuration ►Limit Sts Velocity
► (see below)
Parameter
Display F
OUNDATION
Limit Sts Velocity1 Value ►
--
Lmt Sts Velo1.Status
Limit Sts Velocity1 Value ►
--
Lmt Sts Velo1.Value
<5. Functions>
Active direction: High limit
Set point
Set point - Hysteresis
Time
State 1
Output
State 0
Description of Parameter
Fieldbus
Displays the status of the contact point
output of flow velocity limit switch 1.
Displays the contact point output of flow
velocity limit switch 1.
Process value
Description
IM 01E21A02-03EN
71
Time
F0447.ai