Key facts
- Brand
- testo
- Model
- 6651
- Category
- sensor
- Industry
- Industrial
- Documents
- 2
- Languages
- EN
- Last added
- 2026-11-06
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testo 6651 Ethernet Humidity Transmitter Instruction Manual
The testo 6651 Ethernet humidity transmitter is described in this instruction manual. It is used with plug-in, adjusted probes from the testo 6600 range and can send readings to a control unit via analog outputs while also recording, documenting and visualizing measurement data over Ethernet.
The manual covers specifications and dimensions, scope of delivery and accessories, product description, commissioning including Ethernet communication, operation via the user menu, status, warning and error messages, and maintenance and cleaning. It also refers to the P2A parameterizing, adjusting and analyzing software.
testo 6651 specifications
| Parameters | Humidity (% RH/°Ctd/°Ftd) and temperature (°C/°F) |
|---|---|
| Measuring range | Depends on probe |
| Resolution | 0.1 % RH or 0.1 °C/0.1 °F |
| Voltage supply | 20 - 30 V AC/DC, 300 mA |
| Analog output | 0 ... 10 V ± 15 mV (4-wire), among other options |
| Relay | 4 relays, 250 V AC/DC, 3 A (optional) |
| Display | 2-line LCD with plain text line (optional) |
| Protection class | IP 65 only if the transmitter is wired properly |
| Housing, weight | Plastic, 675 g/1.49 lb |
| Warranty | 2 years |
Source: testo 6651 Ethernet Humidity Transmitter Instruction Manual
All testo 6651 documents by type
Day-to-day operation, settings and troubleshooting. Start here if the product is already set up.
Questions answered in these manuals
What probes is the testo 6651 humidity transmitter used with?
It is used with plug-in, adjusted probes from the testo 6600 range.
From: testo 6651 Ethernet Humidity Transmitter Instruction Manual
What voltage supply does the transmitter require?
The transmitter requires a 20 - 30 V AC/DC supply with 300 mA power consumption.
From: testo 6651 Ethernet Humidity Transmitter Instruction Manual
What is the scope of delivery for the testo 6651?
The scope of delivery includes the key cover, rear panel bracket, Ethernet module, and a CD-ROM with catalogue files and P2A update.
How do I resolve the 'No probe signal' error?
Ensure that the probe connector is fully engaged in the transmitter. If communication still cannot be established, contact Testo Service.