How to Connect an iButton Reader to a GPS Tracker: Guide

Connecting an iButton reader to a GPS tracker is one of the simplest installations there is: just two wires. Even so, one misplaced wire means the device won't read any key, and a wiring mistake can damage the input. In this guide you'll see how to wire it correctly, how to check that it reads, and how to get your drivers' keys working.

For the big picture of the feature (driver identification and 1-Wire temperature), see our iButton and 1-Wire page.

🎯 Who this article is for: installers, tracking companies and fleet managers setting up driver identification with iButton keys.

What you need

• An iButton reader: the socket where the driver touches the key. It has only two wires and needs no power supply.
• DS1990A iButton keys (Dallas/Maxim): each one has a unique 64-bit serial number (a 16-character hexadecimal ROM). They are made of stainless steel, have no battery and last more than 10 years.
• A device with a 1-Wire port: Rinho Spider IoT or Rinho Smart IoT.

Device	1-Wire ports	iButton key support
Spider IoT	1	✅ Yes
Smart IoT	2 (A and B)	✅ Yes, on either port
Zero IoT	—	❌ No (manual or platform-sent driver codes only)

If you're still wondering what an iButton is and how driver identification works, start with our iButton driver identification guide.

The reader's 2 wires: signal and ground

The reader has two contact parts, and each one goes to a wire:

• Center contact (inner) → signal (1-Wire DATA).
• Metal ring (outer) → ground (GND).

On the Spider IoT, the wiring is:

Reader part	Signal	Spider IoT terminal	Pin	Wire color
Center contact	1-Wire DATA	OW	4	Purple
Metal ring	GND	GND	7	Black

The Smart IoT has two 1-Wire ports (A and B), and the key can go on either one. Pin details for each device are in the installation docs: iButton keys on Spider IoT and iButton keys on Smart IoT.

Common installation mistakes

Swapped wires

If you swap the two wires, nothing gets damaged: not the reader, not the key, not the device. But the device won't read any key. And if the reader's ring also touches the vehicle's metal body, the temperature sensor on the same bus stops working too.

Connecting the reader to +12/24 V

⚠️ Important: never connect a reader wire to +12/24 V or to any vehicle positive. The 1-Wire input can't withstand that voltage and will burn out. The reader isn't powered: it only carries signal and ground.

Step 1: check that the device reads the key

First make sure 1-Wire is turned on with >SCXOW1,0< (the first 1 turns the bus on; 0 is the normal mode, which works for both the key and temperature sensors). Then, with the key touching the reader, send this command:

// Query the key present on the 1-Wire port
>QOW00<

// Response: ROW00,<key ROM>,<age>
ROW00,01234567890ABCDE,00

If the device answers with the key's ROM, the wiring is correct. Write down that ROM: you'll need it in the next step.

If you get an error, or the ROM doesn't change when you touch the key, check which of the two wires is ground: it's the one with continuity to the reader's outer ring.

Step 2: register the authorized keys (SICL)

The device stores a list of up to 100 authorized codes (positions 00 to 99), up to 16 characters each. The list is kept in flash memory, so it survives a reboot.

// Store the key in position 00
>SICL00 01234567890ABCDE<

// Add a code in the first free position
>SICL+ 01234567890ABCDE<

// Check what's stored in position 00
>QICL00<

// Delete the code in position 02
>SICL02*<

One important detail: if a code is stored without the $ prefix, the driver session opens automatically when the key is touched. With $, the key doesn't open the session by itself and the SIC command is required. For typical iButton use, store keys without $.

📖 Full reference: ICL command.

Step 3: what the driver session records (QIC)

When a driver touches an authorized key, the device opens a session (one at a time) and records:

• The driver code.
• The identification source (N = iButton/1-Wire, R = RF433).
• Start date and time and total duration.
• Time with ignition off (idle) and time with ignition on (moving).
• Distance traveled in meters.

You can query the current session with:

>QIC<

// Response:
// RIC code,mode,start,duration,idle,moving,distance,slot

The device measures and transmits this data; how it's displayed (per-driver reports, alerts) is set up in your tracking platform. The Rinho protocol also includes an iButton report type (RIB) with position and data.

📖 Full reference: IC command.

Step 4: use the key in the event engine

Driver identification generates signals you can use as triggers in the event engine:

Signal	Meaning
IC00	Session active / inactive
IC01	Mode change
IC02	Login wait timer running / expired
IC03	Failed login (unauthorized code)
ICL00 … ICL99	The driver in that list position was identified
OW00+	Key detected on the port
OWP00 / OWP01	Presence per port

With ICL00…ICL99 you can build rules per person. And with the device's outputs you can, for example, trigger a buzzer, a relay or an immobilizer depending on the key. Here's a documented example:

// Rule 04: when a key is detected, turn on output 0
// and start timer 0 for 10 seconds
>SRL04E;TRG=OW00+;ACC={SXP001}{TD0010}<

💡 Tip: blocking the engine when no valid key is presented isn't a "factory" button: you build it by combining event engine rules, a device output and a relay.

New in firmware 1.09.28: key and temperature on the same wire

With firmware 1.09.28, the iButton key and 1-Wire temperature sensors can be used together on the same wire. It's a new capability that is especially useful on the Spider IoT, which has a single 1-Wire port:

• The key is checked between one sensor reading and the next, roughly every 1 second, so a quick touch of the key isn't missed.
• The same bus can hold up to 8 temperature sensors (positions DT00 to DT07).
• On the Smart IoT, the key can go on either of the two ports.

That way, the same vehicle can identify the driver and monitor cargo temperature with a simpler installation. You'll find both features explained together on the iButton and 1-Wire page, and the temperature side in temperature monitoring.

Frequently asked questions

Does the iButton reader need power?

No. The reader has only two wires: signal (center contact) and ground (metal ring). Never connect it to a vehicle positive.

What happens if I connect the wires the wrong way around?

Nothing gets damaged, but the device won't read any key. Swap the wires and check again with >QOW00<.

How many keys can I authorize on one device?

Up to 100 codes, in positions 00 to 99 of the ICL list. They're stored in flash memory and survive a reboot.

Can I use iButton with the Zero IoT?

No, the Zero IoT has no 1-Wire port. On that device drivers are identified with manual codes or from the platform. Spider IoT and Smart IoT also support Bluetooth identification with the ID Band wristband.

Resources

Rinho Telematics:

• iButton and 1-Wire: driver identification and temperature
• Rinho Spider IoT
• Rinho Smart IoT
• Event engine

Technical documentation:

• iButton key installation on Spider IoT
• iButton key installation on Smart IoT

---

Setting up driver identification in your fleet? Contact us and we'll help you choose the right device and get the installation working.

---

Related articles

• iButton driver identification: complete guide
• Access control and driver management with Rinho
• iButton vs RFID vs BLE: choosing a driver ID system
• Temperature sensors on swappable trailers