Re-Programmable RW1990 RFID Ibutton — One Piece of Hardware, Any Number of Assignments
For property managers, locksmiths, and facility operators who re-issue access credentials every month, every quarter, or every new tenant — and need the hardware itself to be reusable rather than disposable.
Every RW1990 RFID Ibutton ships blank. The 64-bit ROM ID is writable in the field through a standard TM handheld programmer — the same tool a locksmith already keeps in the van. Write a UID, hand the fob to a tenant. Three months later, when the lease ends and a new resident moves in, re-write a different UID onto the exact same piece of hardware and hand it to the next person. No new plastic. No new metal. No ordering another batch because tenant turnover consumed the last shipment. One iButton, unlimited life cycles.
The 16 mm stainless steel iButton housing is crimped into a 15 mm wide injection-moulded ABS handle measuring 55 mm from the key-ring hole to the steel face — same shell geometry as the read-only version, same 1-Wire contact bus, same parasitic-power principle. The difference lies entirely in the silicon: this die accepts a write command through the 1-Wire data line and stores the new UID in non-volatile memory. The programmer software also exposes a write-lock flag — once locked, the newly written UID persists until the lock is deliberately removed with the same programmer. For a student dormitory that rotates occupants every semester, a co-working space that re-issues fobs monthly, or a locksmith who stocks a single SKU and encodes it on demand, this distinction between “burned at the factory” and “written at the job site” is the difference between a sustainable supply chain and a wasteful one.
Three Scenarios Where a Writable Ibutton Pays for Itself
Student accommodation — quarterly rotation, zero waste
A UK university housing operator manages 600 rooms across four halls. Every September, 600 new students arrive. Every June, 600 students leave. An access control integrator pre-encodes 600 RW1990 fobs with UIDs mapped to room numbers in the Iron Logic Matrix-II panel database. Twelve weeks later, at the Christmas vacation swap, 40 students move rooms — forty fobs are re-written on-site using a TM programmer connected to a laptop, re-mapped in the panel, and handed to new occupants. The remaining 560 fobs stay assigned. In June, all 600 are collected, bulk-erased, and stored for the September intake.
If this deployment used factory-burned read-only tokens, every room swap would require a brand-new fob — 40 per quarter, 120 per year, plus the full 600 for the annual intake cycle. With writable hardware, the same batch of 600 fobs serves year after year. At a 600-room scale, annual hardware spend drops from roughly £900 to near zero after the first-year purchase. For any housing operator managing more than 200 rooms with seasonal churn, writable credentials are not a luxury — they are the only supply-chain-viable option.
Locksmith universal stock — one SKU, any site
A locksmith servicing thirty apartment buildings in Berlin carries one box of fifty RW1990 fobs in the van. When a building manager calls — “tenant 14-B lost their key, please replace it” — the locksmith drives to the site, pulls a blank fob from the box, encodes its UID to match the lost credential through a TM handheld programmer, and hands it to the tenant. The Iron Logic panel already recognises the UID because it is a direct clone of the de-authorised one. Total job: one fob, one minute of programming, done.
The locksmith never needs to stock separate SKUs per building, per reader brand, or per UID range. One box covers all thirty buildings because every fob is a blank canvas. This is the business model that turns a random walk-in parts order into a recurring supply relationship — the locksmith buys one box, uses it across the entire client portfolio, and re-orders when the box runs low. No SKU fragmentation. No “wrong UID for this panel” returns. No overnight courier for a single lost key.
Construction site access — changing crews, same hardware
A general contractor runs a twelve-month commercial build with rotating subcontractors: earthworks team in months 1–2, structural steel in months 3–5, MEP in months 6–8, finishing in months 9–12. Each crew receives a colour-coded RW1990 fob — yellow for earthworks, blue for steel — with UIDs registered to a ZKTeco inBio terminal at the site entrance. When the earthworks crew demobilises in month 3, their yellow fobs are collected, bulk-erased, re-encoded with new UIDs, and handed to the MEP crew that arrives in month 6. A box of 200 fobs covers the entire twelve-month project without ordering a single replacement.
Custom Manufacturing — What We Actually Produce In-House
The RW1990 RFID Ibutton is not a white-label import dropped into a retail box. Every unit is assembled end-to-end across five dedicated production lines on a single campus in Shenzhen. The ABS handle is injection-moulded on 120-ton Haitian machines running medical-grade virgin ABS pellets — no regrind, no recycled content. The F5 MicroCan undergoes an eight-station cold-forming process from SUS304 stainless strip, followed by a crimping station that seals the silicon die against the can rim at 12,000 units per shift. The die itself is bonded to the can base with a high-temperature epoxy rated to +85°C continuous — well above the published +75°C operating ceiling.
Customisation is not an afterthought. Silk-print logos are applied on a semi-automatic pad printer with a positioning jig that holds ±0.3 mm registration across a 10,000-unit run. Laser-etched serial numbers are generated per-unit from a database that cross-references the printed serial to the ROM UID tested at QC — every box ships with a CSV mapping file on request. Handle colours can be matched to any Pantone solid coated swatch in runs above 5,000 units, with a colour drift tolerance of ΔE ≤ 2.0 verified on a Konica Minolta spectrophotometer.
Supply Chain — Volume, Consistency, and Why It Matters
Monthly output across all five lines exceeds two million units. This is not a theoretical maximum — it is the sustained average over twelve consecutive months of 2025, verified by shipping manifests and customs declarations available for audit on request. The production campus serves over 340 B2B accounts worldwide, including access control integrators in the CIS region, fleet telematics distributors in the EU, HR attendance system OEMs in Southeast Asia, and a national railway operator in South America that issues RW1990 tokens for track-worker identification at 4,800 signal posts.
For a distributor placing quarterly orders of 50,000 units, this scale means three things. First, lot-to-lot consistency: every batch is manufactured on the same tooling, with the same ABS pellet lot traceable to the resin supplier’s certificate of analysis. Second, price stability: raw material procurement at million-unit volumes locks in SUS304 strip and ABS pellet pricing six months forward, insulating the distributor from spot-market swings. Third, delivery reliability: a 50,000-unit order ships within twenty-one working days because the lines are never fully booked — there is always buffer capacity for existing account holders.
| Parameter | Value |
|---|---|
| Chip | RW1990 — writable 1-Wire ROM, field-programmable via TM handheld tool |
| UID | 64-bit ROM, re-writable with write-lock flag |
| iButton housing | F5 SUS304 stainless steel, Ø 16.0 mm, thickness 5.5 mm |
| Handle | Virgin ABS, injection-moulded, 15 mm wide, 55 mm total length (key-ring hole to steel face) |
| Weight | ~8 g per unit |
| Protocol | Dallas/Maxim 1-Wire, 15 kbps standard / 142 kbps overdrive, Manchester encoding |
| Read method | Touch-contact, parasitic-powered — no battery, no RF field |
| Read speed | < 5 ms at 142 kbps overdrive |
| Write cycles | > 100,000 per memory cell |
| Operating temp | −40°C to +75°C |
| Ingress protection | IP64 (splash-proof); overmoulded IP67 version on request |
| Service life | > 10 years |
| Handle colours | Black, blue, red, yellow, green, white, grey; custom Pantone (MOQ 5,000) |
| Custom marking | Silk-print logo (±0.3 mm registration) + laser-etched serial number with CSV mapping |
| Packing | 100 pcs / inner box; 5,000 pcs / carton (73 × 24 × 33 cm, 25 kg) |
| Monthly capacity | > 2,000,000 pcs across five in-house production lines |
| Ecosystem | Iron Logic, Bolid, Rubezh, ZKTeco, Anviz, Teltonika, Ruptela, Necta, Rheavendors, KONE, Otis |
Quality Assurance — What 2 Million Monthly Units Looks Like at QC
Every outbound batch passes a six-stage outgoing inspection on a random 200-unit sample — double the sampling rate of the read-only line because writable chips introduce an additional failure mode. Stage one: MicroCan geometry is caliper-checked against the F5 tolerance window. Stage two: all 200 units are written with a test UID, read back at both 15 kbps and 142 kbps overdrive, then erased. A single write-read failure triggers a full batch investigation. Stage three: the ABS handle is visually inspected for parting-line burr, sink mark, flash, ring-hole concentricity, silk-print offset, and colour drift under a D65 light booth. Stage four: twenty units are subjected to 500 write-erase cycles each, then re-tested at both speeds. Stage five: twenty units are drop-tested from 1.5 metres onto concrete — any MicroCan-to-handle separation triggers root-cause analysis. Stage six: a random ten-unit cross-section is X-rayed for die-attach voiding. The full QC dossier, including the CSV UID-to-serial mapping file, ships with every pallet.
Frequently Asked Questions
How do I program the RW1990 RFID Ibutton?
Any TM-brand handheld 1-Wire programmer with a probe socket. Connect the programmer to a Windows laptop via USB, launch the TM configuration utility, insert the fob into the probe socket, enter the desired 64-bit UID, and click Write. The total process — from inserting the fob to verifying the written UID — takes under ten seconds per unit. A batch-write mode encodes up to fifty fobs in sequence without re-entering UIDs. The programmer is available as a standalone tool or bundled with your first RW1990 order.
Can the written UID be accidentally overwritten?
Not if the write-lock flag is set. After encoding, the programmer software offers a Lock command that sets a non-volatile flag preventing further writes until deliberately unlocked with the same programmer — a deliberate two-step action that requires physical access to both the programmer and the fob. For most deployments, the workflow is: write UID, lock, deploy. Unlocked fobs accept re-writes freely, which is exactly what you want during the re-encoding cycle between tenants.
Is this the same form factor as the TM1990A-F5?
Identical externally — same 16 mm steel iButton housing, same 15 mm wide ABS handle (55 mm total), same ~8 g weight, same seven stock colours. The only physical difference is the silicon die inside the can. This means any reader, probe, or panel that accepts a TM1990A-F5 accepts an RW1990 without modification. The two SKUs are mechanically interchangeable across the entire 1-Wire reader ecosystem.
What is the minimum order quantity?
Free evaluation samples — ten mixed-colour units plus one TM handheld programmer — ship within three business days to any verified company address. Pilot order: 500 units at standard tier pricing, ideal for testing the re-encoding workflow in your specific deployment before committing to production volume. Full production orders start at 1,000 units. As with all our B2B accounts, the pilot phase is not a gate — it is a verification step that protects both parties.
How long from purchase order to delivery?
Fourteen to twenty-one working days for stocked colours. Custom Pantone adds seven to ten working days. Laser-etched serial numbers with CSV mapping add three working days to the standard lead time. Orders above 10,000 units require twenty-five to thirty-five working days due to production line scheduling. Chinese New Year in January–February extends all lead times by thirty to forty days regardless of volume — plan procurement annually with this window factored in.
What if I need a different chip inside the same shell?
The ABS handle and F5 MicroCan tooling are independent of the silicon — we can load any 1-Wire-compatible die into the same assembly. If your deployment requires EEPROM user memory, a SHA-1 secure hash engine, or a temperature-logging function inside the same 15 mm wide ABS handle form factor, ask for a custom die configuration. Minimum order for a custom silicon load is 20,000 units. Under that threshold, the standard RW1990 writable die is the recommended option.
Request a Free Evaluation Kit
Tell us your deployment scenario — property management, locksmith service, construction site, or custom integration. We ship a ten-unit RW1990 sample kit in mixed handle colours, plus one TM handheld programmer, within three business days to any verified company address. Test the write-erase-rewrite cycle in your own environment before committing to a production order.
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