Input Filtering of MicroLogix 1200 & 1500 PLC
The MicroLogix 1200 and 1500 controllers allow users to configure groups of DC inputs for high speed or normal operation. Users can configure each input group’s response time. A configurable filter determines how long the input signal must be ‘on’ or ‘off’ before the controller recognize the signal. The higher value, the longer it takes for the input state to be recognized by the controller. Higher values provide more filtering, and are used in electrically noisy environments. Lower values provide less filtering, and are used to detect fast or narrow pulses. You typically set the filters to a lower value when using high speed counters, latching inputs, and input interrupts.
Input filtering is configured using RSLogix 500 programming software. To configure the filters using RS Logix 500:
1. Open the ‘Controller’ folder.
2. Open the ‘I/O Configuration’ folder.
3. Open slot 0 (Controller).
4. Select the ‘Embedded I/O Configuration’ tab.
The input groups are pre-arranged. Simply select the filter time you require for each input group. You can apply a unique input filter setting to each of the input groups:
The minimum and maximum response times associated with each input filter setting can be found in controller manual that attached on it.