How Touch Memory key copying works — process and equipment
What actually happens when a TM key is duplicated: reading the 64-bit ROM, choosing the right rewritable blank, the write routine, and verification — plus which copier fits a shop counter, a mixed estate or field batch work.
Duplicating a TM key is not “cloning a chip” — it is writing the master’s 64-bit ROM number into a purpose-made rewritable blank, which then behaves at the door exactly like the original. Five steps end to end:
- Read the master key. The duplicator touches the master and reads its 64-bit ROM — 8-bit family code, 48-bit serial, 8-bit CRC — in a fraction of a second over the 1-Wire contact.
- Pick the blank for the door’s branch. RW1990 for Dallas doors, RW2000 for Cyfral/Metakom, TM08v2 when one blank must cover everything, an OTP blank where re-copying is banned. The wrong blank writes “successfully” but never opens the door.
- Write the ID into the blank. The copier runs the blank’s own write routine (RW1990.1, RW1990.2, TM-01…) to burn the master’s ID into the blank — about three seconds on a counter unit like the TMRF-2RW.
- Verify by reading the copy back. Read the finished copy and compare its ID with the master — units with an LCD show both, which is how a shop proves the write actually took before handing the key over.
- Test on the door. The copy presents the same 64-bit ROM as the master, so a reader cannot tell them apart — if the master opens the door and the copy does not, revisit the blank choice, not the ID.
| Task | Tool | Notes |
|---|---|---|
| Walk-in shop counter, zero training | TMPRG_Easy | One-touch: master blinks red, each blank confirms with blue LED and a beep |
| Mixed estate — TM doors plus 125 kHz RFID | TMRF-2RW | Copies DS1990 → RW1990 and EM4100 → T5577 in one handheld with an LCD |
| Batch pre-coding and issue logs | TMPRG_D | PC batch download over USB, field writing on battery, write-log upload |
| Consumables | RW1990 · RW2000 · TM08v2 · TM-01A | Dallas · Cyfral/Metakom · universal · one-time-programmable |
Can a key be copied without a dedicated device?
No. Writing a blank requires its specific write routine and precise 1-Wire timing that only a duplicator (or a purpose-built programmer) implements. A smartphone cannot do it — TM keys are contact devices, not NFC.
Why can’t the original DS1990A itself be rewritten?
Its 64-bit ROM is lasered at the factory and is physically read-only — no command can change it. That is exactly why copies live on special rewritable blanks such as RW1990, which emulate a DS1990A after writing.
Does a copy behave exactly like the original?
On the door — yes: it presents the same 64-bit ROM and the reader cannot distinguish them. The one difference is that a copy on a standard rewritable blank can itself be re-copied or rewritten; where estates forbid that, one-time-programmable blanks (TM-01A, RW2000) lock after writing.
Can the same device copy RFID fobs too?
A dual-technology unit can: the TMRF-2RW has a contact pad for TM keys and a 125 kHz induction zone that copies EM4100 IDs onto T5577 fobs — one counter device for both branches of a mixed estate.
Related products: TMPRG_Easy · TMRF-2RW · TMPRG_D · RW1990 · TM08v2
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