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ControlLogix Controllers
Controller Memory Use
The following equations provide an estimate of the memory needed for a controller.
| Controller Tasks | _____ * 4000 | = | _____ bytes (minimum 1 task) |
| Digital I/O points | _____ * 400 | = | _____ bytes |
| Analog I/O points | _____ * 2600 | = | _____ bytes |
| Communication modules¬ | _____ * 2000 | = | _____ bytes |
| Motion axes | _____ * 8000 | = | _____ bytes |
| ¬ When estimating memory use by communication modules, count all the communication modules in the system, not just those in the local chassis. This includes device connection modules, adapter modules, and ports on PanelView terminals. | |||
Additional 1756-L55 Memory
The 1756-L55 controllers do not operate standalone. Choose one of these memory boards to come already assembled with the controller. You can also order additional memory boards either for spare parts or to upgrade existing 1756-L55 controllers.
The 1756-L6x controllers have a fixed RAM size and do not use a memory board. Use a CompactFlash card for nonvolatile storage.
| Catalog Number | Supported Controller | Battery-backed Static RAM | Nonvolatile RAM |
| 1756-M12¬ | 1756-L55 | 750 KB | None |
| 1756-M13 | 1756-L55 | 1.5 MB | None |
| 1756-M14 | 1756-L55 | 3.5 MB | None |
| 1756-M16 | 1756-L55 | 7.5 MB 3.5 MB for tag data |
None |
| 1756-M22¬ | 1756-L55 | 750 KB | 750 KB |
| 1756-M23T | 1756-L55 | 1.5 MB | 1.5 MB |
| 1756-M24T | 1756-L55 | 3.5 MB | 3.5 MB |
| 1784-CF64 | 1756-L6x‡ | None RAM contents are written to internal Flash during power down |
Same as the memory limit for the controller |
| ¬ The 1756-L55 controller must have firmware revision 10 or later. T The 1756-L55 controller must have firmware revision 8 or later. ‡ You can use CompactFlash with the 1756-L61, 1756-L62, 1756-L63, and 1756-L60M03SE controllers. The 1756-L61, 1756-L62 controllers require firmware revision 12 or later. The 1756-L63 controller requires firmware revision 11 or later. The 1756-L60M03SE controller requires firmware revision 13 or later. |
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CompactFlash Memory
The CompactFlash card offers nonvolatile memory (flash) to permanently store a user program and tag data on a controller.
- 1784-CF64 has 64 MB of memory.
- 1784-CF128 has 128 MB of memory.
The 1756-L55M2x controllers have fixed internal nonvolatile memory.
The 1756-L6x controllers support a removable CompactFlash card for nonvolatile memory. You install the 1784-CF64 card in a socket on the controller. The CompactFlash card stores the user program, tag data, and controller firmware. This lets you upgrade firmware on a 1756-L6x controllers without using RSLogix 5000 software or ControlFlash software.