Allen-Bradley 1762-MM1RTC MicroLogix 1200 Memory Clock Module

The Allen-Bradley 1762-MM1RTC is a dual-function expansion module designed for the MicroLogix 1200 programmable logic controller system. It combines a 6 Kbyte flash memory storage area with a real-time clock (RTC) circuit, providing program back-up capability alongside time-based control. The module snaps directly into the processor's memory module port, retaining critical user data and maintaining system time during main power outages.

Dual Storage and Real-Time Clock Architecture

The 6 Kbyte non-volatile flash memory allows operators to store user programs and controller data for transport, backup, or field program updates. Integrated write-protection capabilities prevent accidental data modification during transfer operations. The real-time clock unit operates with 1-second resolution to maintain system-wide temporal tracking across year, month, day, day of the week, hour, minute, and second.

Power Maintenance and Hot Swapping

Power for the timekeeping circuit is maintained by an internal 3.0 VDC lithium battery when main operational power is removed. The module is engineered for hot-swappable installation, enabling maintenance technicians to insert or remove the module under operational bus power without interrupting controller execution or risking electrical fault.

Technical Specifications

Functional Application and System Integration

By installing the 1762-MM1RTC, MicroLogix 1200 controllers gain temporal scheduling features to trigger event-driven sequences based on precise calendar times. Memory program transfer completes in under 500 milliseconds, allowing fast program execution upon initial boot or module transfer. Operating power is drawn directly through the memory port connection within a 4.5 VDC to 5.5 VDC range, consuming 0.025 Watts during operation.

Installation Guidelines

Before installing the module into a MicroLogix 1200 base unit, remove the protective cover from the memory module slot located on the front panel. Align the module connector pins with the internal socket and press firmly until fully seated. Ensure the retaining tabs latch securely to maintain mechanical stability in high-vibration environments.

Frequently Asked Questions

Q: Can the 1762-MM1RTC be replaced while the MicroLogix 1200 base unit is powered up? A: Yes, the 1762-MM1RTC supports hot swapping, allowing removal or insertion under power without shutting down the controller.

Q: How does the 1762-MM1RTC maintain time accuracy during a facility power outage? A: The module contains an internal 3.0 VDC lithium battery that independently powers the clock circuit when main system power is disconnected.