How to wire a Touch Memory reader (TM+, TM−, LED)
Check the supplied reader diagram for data, ground and LED connections. Wire colours and pin numbers vary by device; confirm controller requirements before connecting a Touch Memory reader.
| Pin | Type | Protocol | Typical use |
|---|---|---|---|
— | See supplied diagram | TM + | Identify the data contact and controller input from both device diagrams. Do not infer the connection from wire colour. |
— | See supplied diagram | TM − | Confirm the data return and grounding arrangement in the supplied diagrams, including any isolation requirements. |
— | See supplied diagram | LED + | If an independent LED connection exists, confirm its polarity, voltage and current-limiting arrangement from the device documentation. |
— | See supplied diagram | LED − | Identify the LED return from the reader diagram; do not assume it shares the data return. |
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The LED is not powered by the key
Some readers have independent LED wiring. Confirm how that model drives its indicator and whether it can read with the LED disconnected. An illuminated LED alone does not prove that the controller read or accepted the key.
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Reversing TM+ and TM− looks like a dead reader
With power removed, verify the data and return connections against the supplied reader and controller diagrams. Wire colours are not a universal standard. Incorrect wiring is one possible cause of a read failure; test before replacing parts.
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Respect 1-Wire cable limits
Cable length, topology, capacitance and pull-up design affect communication. Follow the controller documentation and test the intended cable arrangement. Do not add resistors or assume another device’s bus limits apply without checking the circuit requirements.
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Check the signal return
Check the documented return path and isolation requirements between the reader, controller and power supply. Correct an identified wiring fault according to the manufacturer’s diagram, then repeat the reading test.
Mounting the reader
The illustration shows one flanged-reader installation. Confirm the cut-out, fasteners, sealing and cable route against the supplied reader drawing and the mounting surface before fitting.
Sourcing fixed-ID keys for your reader or controller project? Review the product and sample-check requirements: TM1990A-F5 · TM1990A-F5 for equipment projects
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