This project contains a Structured Text (ST) file named BuildTimeStampUDFB.st.
BuildTimeStampUDFB.st is a User Defined Function Block (UDFB) for Rockwell Automation Micro800 PLCs. It generates a unique timestamp string from the PLC's Real Time Clock (RTC) in the format YYMMDDSSSSS (YY=year, MM=month, DD=day, SSSSS=seconds since midnight, all zero-padded). This is useful for versioning, diagnostics, and logging in automation projects.
Below is a visual representation of the UDFB's variables as seen in Connected Components Workbench:
- Inputs:
FBEN(BOOL): Function Block Enable. Set to TRUE to execute the timestamp generation.
- Outputs:
FBENO(BOOL): Set to TRUE when the timestamp has been generated.TimestampStr(STRING[12]): The generated unique timestamp string in the format YYMMDDSSSSS.
- Internal:
stRTC(RTC): Structure holding RTC data (populated by RTCREAD).SecondsSinceMidnight(DINT): Calculated seconds since midnight.
To use the UDFB in a ladder logic program, instantiate it as shown below. The following image demonstrates the UDFB in a typical Micro800 ladder logic environment:
- Enable the function block with
FBEN := TRUE. - When
FBENOis TRUE,TimestampStrcontains the generated timestamp.
For June 14, 2025, at 15:28:51:
- Year: 25 → "25"
- Month: 06 → "06"
- Day: 14 → "14"
- Seconds since midnight: 153600 + 2860 + 51 = 55731 → "55731"
- Output:
TimestampStr = "25061455731"
BuildTimeStampUDFB.st: Main Structured Text file containing the UDFB implementation.Images/UDFB_Vars.png: Screenshot of the UDFB variable table.Images/UDFB_In_Ladder.png: Screenshot of the UDFB in a ladder logic program.
- Rockwell Automation Micro800 PLC
- Connected Components Workbench (CCW)
- IEC 61131-3 Structured Text support
- Real Time Clock (RTC) must be available in the PLC
This code is released under the The Unlicense. You are free to use, modify, and distribute it without restriction.
Adam G. Sweeney
Generated on June 14, 2025.