Problem Description
The ControlLogix L35E controller experiences date corruption where the year spontaneously changes to 2117 while the day and month remain accurate. This issue occurs on controllers running RSLogix 5000 / Studio 5000 firmware revision v20.011 (20 major, 11 minor). The problem manifests even when the controller has continuous power and a healthy battery, ruling out battery failure or memory card boot issues.
Root Cause Analysis
The date jumping to year 2117 is a known firmware-level anomaly in ControlLogix L35E controllers running firmware v20.011. The issue stems from improper handling of the controller's internal real-time clock (RTC) tick counter, which can overflow or corrupt under specific conditions during extended runtime without controller power cycles or resets.
| Parameter | Value |
|---|---|
| Affected Controller | 1756-L35E / 1756-L35ER |
| Affected Firmware | v20.011 (20.011) |
| Fixed Firmware | v20.019 (20.019) |
| Known Anomaly | Technote 629159 |
| Symptom | Year displays as 2117 |
Solution: Firmware Upgrade
Rockwell Automation corrected this anomaly in firmware v20.019. Upgrade the controller firmware using RSLinx Classic or ControlFlash Plus following these steps:
- Open RSLinx Classic and verify communication to the L35E controller
- Launch ControlFlash Plus or use Menu > Tools > Firmware in RSLogix 5000
- Select the appropriate firmware revision: Series C, FRN 20.019
- Confirm the catalog number: 1756-L35E / 1756-L35ER
- Complete the firmware flash process (controller automatically reboots)
- After reboot, verify the date in Controller Properties > Date/Time
Alternative Workaround: PanelView Date Sync (Not Recommended)
If firmware upgrade is not immediately feasible, some users attempt syncing date from a PanelView Plus HMI to the controller using the SSV (Set System Value) instruction with the WALLCLOCKTIME object. However, this approach has significant limitations:
- Remote Date/Time Global Connection in FactoryTalk View is unidirectional: HMI updates from controller, not controller from HMI
- Retrieving PV date into PLC requires custom VBA scripts or data transfer objects
- This workaround is complex and does not address the root RTC firmware issue
Rockwell Automation recommends firmware upgrade over this workaround for permanent resolution.
Verification Steps
After applying the fix:
- Open RSLogix 5000 / Studio 5000 Logix Designer
- Right-click the controller > Properties > Date/Time
- Verify the year displays correctly (current year, not 2117)
- Monitor over 24-48 hours to confirm date stability
- Test any AOI relying on date/time (e.g., Day of Week) for correct operation
What causes the ControlLogix L35E year to change to 2117?
This is a known firmware anomaly in version v20.011 (Technote 629159) causing the real-time clock to corrupt. The issue is fixed in firmware v20.019.
Can a bad battery cause the date to change to 2117?
No. A bad battery typically causes loss of program and tag data, not date corruption to 2117. The 2117 symptom specifically indicates the firmware anomaly.
Does the Day of the Week AOI cause the date to change?
No. The AOI reads the controller's WALLCLOCKTIME but does not cause the date corruption. The root cause is the firmware anomaly, unrelated to any Add-On Instruction.
Can I use PanelView Remote Date/Time to fix the controller date?
No. The Remote Date/Time Global Connection only pushes controller time TO the PanelView, not the reverse. This cannot fix the controller's corrupted date.
What firmware version fixes the 2117 date issue?
Upgrade to firmware v20.019 or later. This resolves the RTC anomaly described in Technote 629159.