The 1764-MM3RTC is a MicroLogix 1500 Memory and real-Time Clock (RTC) module. This module is an accessory module that is used to provide a non-volatile, 16 KB user memory and RTC for use in implementing scheduled or time-dependent applications beyond the capabilities and timing of counting and timer instructions. The 1764-MM3RTC 16KB non-volatile memory provides independent memory storage, not relying on the power applied to the controller or battery to retain its contents. With this, the 1764-MM3RTC contributes to increased uptime and prevents the unwanted erasure of user programs that typically occurs due to power surges and loss of memory retaining energy to the Random Access Memory (RAM) area. The 1764-MM3RTC Real-Time Clock (RTC) allows the implementation of time and day-dependent logic. This type of logic is typically implemented in Heating and Ventilation and Airconditioning (HVAC) applications wherein Duplex or Triplex equipment arrangements are operated in shifts or schedules to evenly distribute runtime hours and manage mechanical wear and tear. This scheduled operation is beyond the capabilities of timers and counters. The 1764-MM3RTC has a dedicated function file in the controller for direct and simple integration to the user program. It has an accuracy that is dependent to the ambient temperature specifically, +34 to -70 seconds/month at 0°C (+32°F); +36 to -68 seconds/month at +25°C (+77°F); +29 to -75 seconds/month at +40°C (+104°F) and -133 to -237 seconds/month at +55°C (+131°F). The RTC component has an internal, non-replaceable battery with a battery low indicator bit via the address RTC:0/BL.

The 1764-MM3RTC MicroLogix 1500 Memory Module with a real-time clock by Allen-Bradley is a memory module for the 1500LRP MicroLogix controller which allows for program backups and confers data downloads and memory protection for safety. The 1764-MM3RTC has a 16KB maximum memory size and the real-time clock (RTC) provides Year, Month, Week, Day, Hour, Minute, and Second information to the function file in the 1500LRP MicroLogix controller. The real-time clock has a temperature-dependent accuracy of +34 to -70 seconds/month at 0 Deg. C (32 deg F), through -133 to -237 seconds/month accuracy at 55deg. C (131 deg. F). The real-time clock has an internal battery that provides backups for stored time-stamped data, and its battery has a 5-year minimum lifespan when used at a temperature range of 0-40 deg. C (32-104 deg. F). The 1764-MM3RTC can only store 1 user program at a time, and it is capable of providing application memory security because it prevents the controller from execution if the program on the memory module does not match the one on the controller. The 1764-MM3RTC also supports a read many and write once function, and it is designed to remain undamaged if it is removed at any time from the controller. It has an operating temperature range of 0-55deg. C (32-131 deg. F), at 5-95% non-condensing relative humidity, and is built for storage at a temperature range of -40-85deg. C (-40-185 deg. F)

1. What is the size of non-volatile memory available to the 1764-MM3RTC?

The 1764-MM3RTC has 16 KB memory.

2. What is the accuracy of the RTC component of the 1764-MM3RTC?

The 1764-MM3RTC RTC component has accuracy of +34 to -70 seconds/month at 0°C (+32°F); +36 to -68 seconds/month at +25°C (+77°F); +29 to -75 seconds/month at +40°C (+104°F) and -133 to -237 seconds/month at +55°C (+131°F).

3. Does the 1764-MM3RTC support insertion and removal under power?

Yes. The 1764-MM3RTC can be installed with or without power applied to the controller.