1764-MM2RTC

Technical Specifications for 1764-MM2RTC

Manufacturer:	Rockwell Automation
Brand:	Allen-Bradley
Product Family:	MicroLogix 1200
Product Type:	Memory Module
Part Number:	1764-MM2RTC
Supported controllers:	1764-L24AWA; 1764-L24BWA; 1764-L28BXB
Supported controllers:	1764-LRP; 1764-LSP
Allowable Functions:	User Program and Data Back-up, User Program Compare, Data File Download Protection, Memory Module Write Protection and Removal/Insertion Under Power
Real Time Clock Accuracy:	0 ¡C or +32 ¡F, accuracy is +34 to -70 seconds/month. For +25 ¡C or +77 ¡F, accuracy is +36 to -68 seconds/month, for +40 ¡C or +104 ¡F, rated accuracy is +29 to -75 seconds/month and at +55 ¡C or +131 ¡F, accuracy is -133 to -237 second
Mounting:	Memory Module slot
User Memory:	16 Kbytes
Operating Temperature:	0-55 deg.C
Support automatic loading:	Yes
Support for removal under power:	Yes
System Status File:	S:2/9 Memory Module Program Compare
Control Bits:	Load Memory Module on Memory Error S:1/10 Load Memory Module Always S:1/11 On Powerup, Go to run S:1/12
system Overhead:	80 µs
Configuration Software	RSLogix 500;

About 1764-MM2RTC

The Allen-Bradley 1764-MM2RTC is a memory module with real-time clock included. This module is a cost-effective solution for implementing time and date-based automation and providing a non-volatile memory to the controller. Real-Time clock and memory modules are installed in the memory module slot of the MicroLogix 1500 base unit. MicroLogix 1500 controllers are provided with only One (1) memory module slot. With the use of a combination memory and clock module, both module may be installed at the same time unlike separate modules such as 1764-MM1 and 1764-RTC which will individually occupy the single module slot. The memory module has 8KB non-volatile EEPROM type memory. With this memory type, the contents of the programmable cannot be easily erased as non-volatile memory do not need a battery to retain its contents. The primary use of this memory module is to provide data and program backup to the controllerÕs internal memory which is retained by a lithium battery. When the lithium battery fails, the contents of the internal memory will be erased once power is removed from the controller. Memory Module information are kept in the Memory Module Information file. The contents of this file includes the Feature, Corresponding address, Data Format, Type and User Program Access. Parameters include FT - Functionality Type, MP - Module Present, WP - Write Protect, FO - Fault Override, LPC - Program Compare, LE - Load On Error, LA - Load Always and MB - Mode Behavior. One important parameters within the Memory Module File is the Module Present (MP) variable. This bit can be used and included in the user program to monitor if the memory module is continuously detected by the controller. This may be used as diagnostic information to the health of the memory module. Other allowable functions of the memory module include User Program Compare, Data File Download Protection, Memory Module Write Protection and Removal/Insertion Under Power. The Real-Time Clock (RTC) has an accuracy of 0 ¡C or +32 ¡F, accuracy is +34 to -70 seconds/month. For +25 ¡C or +77 ¡F, accuracy is +36 to -68 seconds/month, for +40 ¡C or +104 ¡F, rated accuracy is +29 to -75 seconds/month and at +55 ¡C or +131 ¡F, accuracy is -133 to -237 seconds/month. These values are expected worst case values over a 31-day period. It is commonly used to implement scheduling of energization and actuation of Final Control Elements (FCE) such as pump, compressors, motors and other similar devices and equipment. This approach is most commonly applied in Heating Ventilation and Air Conditioning (HVAC) systems where runtime hours must be equally distributed to devices and equipment as well as promote an efficient operation. Similar to the Memory moduleÕs information file, the Real Time Clock also has information file where data of the RTC is stored. Data stored are YR - RTC Year with range of 1998-2097, MON - RTC Month with range of 1-12, DAY - RTC Day of Month with range of 1 to 31, HR - RTC Hours with range of 0 to 23 (military time), MIN - RTC Minutes with range of 0 to 59, SEC - RTC Seconds with range of 0 to 59, DOW - RTC Day of Week with range of 0 to 6 (Sunday to Saturday), DS - Disabled with value select ion of 0 to 1 and BL - RTC Battery Low with Boolean range of 0-1.