The Rate Limit function creates an output that follows the input but prevents the output from changing faster than the specified rates. The function block can be used, for example, to stabilize a sensor value. The output moves at a maximum allowed rate towards the new input value each second.
Figure 1: RateLimit - Function Block |
Figure 2: RateLimit - Property Sheet |
When the Rate limit is configured, the output will move at a maximum allowed rate towards the new input value each second.
Figure 3: RateLimit Logic Diagram
Inputs
Input Name |
Description |
Enable Bypass |
If it is set to "true", the output Out is set to the Bypass Value independent of Duration and Up or Down Rate. Range:
|
In |
The In value is the base for the output Out. The output Out follows the In considering the Up/Down Rate and the optional Duration timer. If In has a value of "null", "+inf" or "-inf", then Out is set immediately to the In value irrespective of the Up/Down Rate and the Duration Timer. Similarly, if In changes from quot;null", "+inf" or "-inf",to a valid value; the valid value is immediately set on Out. Note: If a temperature value is connected at the input In, which is read in via a Ui Terminal, this value can have the value +inf/-inf for Sensor Open/Short. The +-inf values are immediately passed to the output Out. |
Duration (In & Par) |
This value defines a time after which the Out jumps to the In value. If the Duration timer is running (Running Time is increasing), the output follows the input in the defined Up/Down Rates. When the duration time has expired, the output receives the value from the input, which will result in a jump. The running Duration timer is shown on Running Time. If Duration = 0, Out follows the In value with the specified Up/Down rate without the jump. Range: 0-259200 sec (48h) |
Bypass Value (In & Par) |
If the Enable Bypass input is "true", the Out is set to this value independent of Duration and Up/Down Rate. |
Up Rate (In & Par) |
If In value is greater than the Out value, Out value follows the In value according to Up Rate. If Up Rate is "0", Out = In, if In > Out. |
Down Rate (In & Par) |
If In value is less than the Out value, Out value follows the In value according to Down Rate. If the Down Rate is 0, then Out = In, if In < Out. |
Table 1: Inputs of RateLimit Function
Outputs
Output Name |
Description |
Out |
The Out follows the In considering the Up/Down Rate and the optional Duration timer. |
Running Time |
The timer is started from 0 sec with each new In value and timer value remains, if Out is reached the In value. |
Table 2: Outputs of RateLimit Function
Parameters
Parameter Name |
Description |
Duration Par (In & Par) |
If input Duration is "null", Duration Par is used as parameter. Default = 0 sec. |
Bypass Value Par (In & Par) |
If the input Bypass Value is "null", Bypass Value Par is used as parameter. Default = "null" (-> Out = In). |
Up Rate Par (In & Par) |
If Up Rate is "null", Up Rate Par is used as parameter. Default = 0 changes / sec |
Down Rate Par (In & Par) |
If Down Rate is "null", Down Rate Par is used as parameter. Default = 0 changes / sec |
Out Save |
Master Sync Enabled : If you set it to "true" the last output will be set as output for one cycle after the controller restarts. The application can use it to return to the same state before the controller restart. Out: To enable or disable the Out feature. |
Table 3: Parameters of RateLimit Function
Examples
After the complete cycle of Up Rate/Down Rate and the duration is completed, input will pass in to output without any delay.
While the ramp up cycle, it ramps down based on Up Rate Par value.
While the ramp up Cycle it will ramp down based on "down rate parameter value"
While the By pass Override, output will change without any delay
Refer to General Description for general information about IRMN4 Function Blocks.