The best reading in the world is no use stuck in the sensor
A sensor can measure accurately and still fail to deliver useful data if its output is incompatible with the receiving system. The appropriate choice depends on more than the parameter being measured. Electrical interface, communications protocol, cable distance, power availability, update rate and fault reporting all affect how reliably the measurement can be used.
Gill sensors support a range of analogue and digital interfaces, including Modbus RTU, SDI-12, NMEA 0183, RS232, RS422, RS485, CAN and analogue voltage or current outputs, depending on the model and configuration.
How do you choose the output for a sensor?
Choose a sensor’s output by starting with the system that will receive it. A PLC may expect Modbus registers, an environmental logger SDI-12, marine navigation equipment NMEA 0183, a vehicle controller CAN and an older installation 4 to 20 mA. The interfaces are not interchangeable, and the output is usually fixed when the sensor is ordered.
Integration is easiest to get right when the host system is understood before the sensor is specified. A PLC may expect a Modbus register map. An environmental logger may require SDI-12. A vessel’s navigation equipment may use NMEA 0183, while a vehicle controller may communicate over CAN. An existing installation may accept only a 4 to 20 mA signal.
These are not interchangeable options. Each has its own electrical requirements, data structure and limitations, and the available outputs vary between sensor models.
The first step is therefore to establish what the receiving system can accept, what information it needs and how that information will be used. The sensor can then be selected around those requirements.
What needs to be established?
| Consideration | What to establish |
|---|---|
| Host interface | Which electrical inputs and communications protocols does the receiving equipment support? |
| Measurement data | Does the system need one measurement or several parameters, together with status information? |
| Cable route | How far must the signal travel, and what electrical conditions will it encounter? |
| Power | What supply is available, and are there restrictions on consumption? |
| Update rate | How quickly must new measurements reach the host? |
| Fault handling | How will the system distinguish a valid reading from a sensor fault or loss of communication? |
| Configuration | Is the required output available on the chosen model, or must a different variant be specified? |
Resolving these questions early is generally easier than adapting an installation after the sensor has been selected.
Choosing the right output
Different interfaces suit different systems. The best option is usually the one the receiving equipment already supports, provided it meets the requirements for distance, data, power and diagnostics.
Analogue voltage and current
Analogue outputs such as 0 to 5 V, 0 to 10 V and 4 to 20 mA are widely understood by industrial controllers, displays and data acquisition equipment. They are useful where the host needs a straightforward representation of one measured value.
A current loop can be suitable for longer cable runs and electrically demanding environments, subject to the installation design and the output’s specified load limits. The trade-off is that each channel normally carries one value, with limited diagnostic information compared with a suitable digital interface.
Consider analogue when: the receiving system already has compatible inputs and needs a simple, established signal.
0 to 5 V | 0 to 10 V | 4 to 20 mA
Serial communications and Modbus RTU
RS232, RS422 and RS485 describe electrical interfaces, rather than complete data protocols. The distinction matters when checking compatibility: two devices using RS485, for example, still need to agree on the communications protocol and data format.
Modbus RTU is commonly used in industrial control, SCADA and building management systems. It allows a host to request multiple values through a defined register structure, where supported by the sensor. Digital interfaces can also provide status or diagnostic information that an analogue signal may not convey.
RS232 is generally associated with shorter point-to-point connections. RS422 and RS485 can suit longer or more demanding cable routes, depending on the network design and installation conditions.
Consider digital communications when: the host needs several measurements, structured data or status information over a shared interface.
RS232 | RS422 | RS485 | Modbus RTU
SDI-12 for environmental monitoring
SDI-12 is used with environmental and hydrological data loggers. It supports low-power measurement systems and allows compatible sensors to share a data line.
For remote monitoring stations, the logger’s existing SDI-12 capability can be an important selection criterion. However, compatibility still depends on the particular sensor model, supported commands, power requirements and logger implementation.
Consider SDI-12 when: integrating with a compatible environmental logger or remote monitoring system.
SDI-12
NMEA 0183 for marine systems
NMEA 0183 is used to exchange data between marine instruments and navigation systems. A compatible output can allow wind measurements to be incorporated into a vessel’s existing instrumentation.
Check the required sentence types and update rate as well as the electrical interface. Support for NMEA 0183 should not be assumed simply because a sensor has a serial output.
Consider NMEA 0183 when: the receiving equipment is designed to use this marine data format.
NMEA 0183
CAN for vehicles and machinery
CAN is widely used for communication between electronic control units in vehicles and machines. It can carry structured messages between compatible devices, but integration depends on the specific network implementation, message definitions and configuration.
A CAN output is not automatically compatible with every CAN-based system. The host requirements and the sensor’s supported message format must be checked together.
Consider CAN when: the sensor is being integrated into a compatible vehicle or machine control architecture.
CAN
Comparing common sensor interfaces
The table below provides a starting point for specification. It does not replace checking the current datasheet and exact product configuration.
| Consideration | Analogue voltage or current | Modbus RTU | SDI-12 | NMEA 0183 | CAN |
|---|---|---|---|---|---|
| Typical receiving system | PLCs, displays and legacy controllers | PLCs, SCADA and building management | Environmental data loggers | Marine navigation systems | Vehicle and machine controllers |
| Data carried | Typically one value per channel | Multiple values through registers | Values returned through supported commands | Data in supported sentences | Data in defined messages |
| Diagnostic capability | Usually limited | Depends on registers and implementation | Depends on supported responses | Depends on sentence and implementation | Depends on messages and implementation |
| Main selection check | Input range and electrical loading | Register map and communications settings | Logger compatibility and supported commands | Required sentences and update rate | Network and message compatibility |
| Gill examples | WindSonic analogue options, LevelPro, WearDetect | WindSonic, WindUltra, WindObserver, MetConnect, WearDetect | WindSonic, WindUltra, MetConnect | WindSonic, MetConnect | LevelLite, WearDetect CANbus |
The exact outputs available depend on the product and its order configuration. For example, the WindUltra datasheet order codes list digital outputs only, so it should not be assumed to suit an analogue-only installation. Confirm the required output before placing an order.
Design the integration before installation
More than a protocol
A successful integration depends on more than choosing a protocol. Wiring, power supply, grounding, communications settings, data handling and fault response all need to work together.
Settings for every interface
For digital interfaces, establish the required baud rate, data format, addressing and register or message definitions where applicable. For analogue signals, check the output range, receiving input, load requirements and scaling. For every interface, consider cable routing, environmental conditions, update rate and how the system behaves if data is interrupted.
Faster is not free
Higher update rates may increase data volume and power demand. The fastest available setting is not necessarily the right one: it should be selected according to the dynamics of the measurement and the decision the data supports.
Outputs are fixed at order
Output configuration is also important at the point of order. Many sensors are supplied with a specified output variant, and changing interface later may require a different product configuration rather than a software setting. Confirm this before finalising the bill of materials.
Gill sensors and their output options
The following examples illustrate how output selection varies across the Gill range. Confirm the current datasheet and order code for the exact configuration required.
WindSonic
Options for different host systems
WindSonic is available with a range of output options for environmental monitoring, industrial integration and OEM applications. Depending on the model and configuration, these include serial interfaces, analogue outputs, SDI-12 and Modbus RTU.
The breadth of options makes WindSonic worth considering when the wind measurement is established but the receiving system varies between projects. It is still necessary to select the correct output variant for each installation.
MetConnect
Bringing measurements into one system
MetConnect combines weather measurement with interfaces for integrating compatible external sensors. It can accept supported inputs and provide data to the wider system through the configured output.
Exact combinations and input compatibility should be confirmed for the selected configuration. MetConnect is worth considering where a project needs to bring several environmental measurements together rather than connect each sensor independently to the host.
LevelLite
Level sensing for vehicles and machinery
LevelLite is a capacitive level sensor intended for applications including vehicles and machinery, with voltage and current outputs. RS232 is used for configuration and CAN is available on bespoke sensors.
The appropriate variant depends on the receiving controller and the required electrical interface. For CAN integration, check the network and message requirements. For analogue integration, confirm the signal range and the controller’s input specifications.
Other Gill products: output choice also matters across other sensor families, including WindObserver, WindUltra, LevelPro and WearDetect. Their available interfaces differ by model and configuration, so the most useful starting point is the specific product datasheet rather than assuming that an output supported elsewhere in the range will also be available.
If a standard option does not match the host system, discuss the requirements with our team before committing to the design.
insight
What happens when the measurement is wrong?
Integration is not complete when a value appears on a screen. The receiving system also needs a way to identify invalid data, loss of communication and sensor faults.
A zero wind-speed reading, for example, could represent calm conditions. Depending on the output and system design, a similar-looking value might also result from a wiring fault or another failure. An analogue signal alone may not provide enough information to distinguish these cases.
Digital outputs can carry status information alongside measurement data, where the particular product supports it. Gill wind sensors provide instrumentation status information with their outputs, and Blade position sensors report whether the activator is within range. The host must be configured to interpret this information and act on it appropriately.
For an unattended installation, that could mean flagging a suspect reading, raising a maintenance alert or excluding invalid data from a calculation. The appropriate response depends on the application and the receiving system.
When specifying an interface, ask two questions: how will the system use the measurement, and how will it recognise when that measurement cannot be trusted?
Related products and resources
Application noteAN0051 Remote data collection
Getting sensor data into data monitoring systems.
Application noteAN0012 Control of building HVAC
Wind data feeding building management systems.
ApplicationCatchment and hydrometeorology
Sensors on environmental data loggers.
ResourcesSoftware and configurators
Configuration tools for Gill sensors.
Speak to our team
Tell us what you need to measure, where and under what conditions. We’ll help you work out the appropriate approach.
Integration questions
Start with the receiving system. Confirm its supported electrical interfaces and protocols, then check the data required, cable distance, power supply, update rate and diagnostic needs. Select a sensor variant that supports the complete requirement.
They are different electrical interfaces used for serial communication. They differ in how signals are transmitted and the connection arrangements they support. They are not data protocols in themselves, so the receiving equipment must also support the sensor’s data format and communications settings.
No. Modbus RTU is a communications protocol; RS485 is an electrical interface. Modbus RTU commonly operates over RS485, but matching the electrical interface alone does not guarantee compatibility. The host and sensor must also agree on the protocol and register definitions.
A 4 to 20 mA signal can suit industrial systems that need a straightforward measurement input and already use current loops. A supported digital output may be preferable when the host needs multiple parameters or status information. The choice depends on the host’s capabilities and the requirements of the installation.
Not necessarily. Many models are supplied with a specified output configuration, and a different interface may require a different variant rather than a software change. Confirm the required output and order code before purchase.
A digital output can provide status or diagnostic information where the product supports it. Whether a particular fault can be identified depends on the sensor, the data provided and the receiving system. The host must be configured to interpret the status and determine the appropriate response.
SDI-12 options are available for applicable WindSonic, WindUltra and MetConnect configurations. Check the current datasheet and order code for the exact model, as interface availability varies.
They can connect directly where the sensor’s output is compatible with the PLC’s electrical inputs and supported protocol. Otherwise, additional interface hardware or a different sensor configuration may be required. Confirm both the electrical and data requirements before installation.
Provide the measurement required, the receiving system make and model, available inputs and protocols, cable distance, power supply, required update rate and any diagnostic or environmental requirements. An existing wiring diagram or interface specification can also help establish compatibility.