Decoding Sensor and Instrumentation Communication Protocols Webinar Recap

The Interface technical webinar, Decoding Sensor and Instrumentation Communication Protocols provides valuable insights into the relationship between measurement technologies and communication. The following recap highlights key topics detailed during the event, which you can now watch on our YouTube channel.

Keith Skidmore, Interface’s engineering expert in applications and solutions, highlights the types of communication protocols and examples of connecting sensors to instrumentation in different environments. The technical conversation starts with a brief overview of analog and digital considerations. Analog continues to be the most popular communication output in test and measurement; however, digital is rapidly catching up due to changing networking options.

Breaking down the variations of Fieldbus Protocol Options helps set the framework for the numerous communication standards available to test and measurement professionals. Here are those we referenced in the webinar.

• Analog
• USB / Virtual Serial Port
• RS485 / RS232 serial
• Modbus RTU (RS485)
• Modbus TCP
• CANbus, CANopen
• Device Net
• CC-Link
• PROFIBUS DP
• PROFINET IO
• Ethernet TCP/IP
• Ethernet/IP
• EtherCAT, EtherCAT P
• POWERCAT
• SERCOS III

CONFIGURATION CONSIDERATIONS: NAVIGATING THE COMPLEXITIES

STEP 1: IDENTIFY THE COMMUNICATION PROTOCOL

The communication protocol to transmit data from the load cell to the data acquisition system should be compatible with the other equipment in the test environment. The distance between the load cell and instrumentation is critical, as some protocols have limitations in cable length. Select the communication protocol based on the application’s specific requirements. Some protocols may require additional hardware. Response rates, predictability, flexibility, and remote accessibility will determine the best type of protocol to select.

STEP 2: DEFINE ACCURACY AND PRECISION APPLICATION REQUIREMENTS

The accuracy and precision requirements vary depending on the application. High accuracy and precision load cells are essential in a precision test environment, such as a laboratory or calibration facility. In contrast, load cells with lower accuracy and precision may be sufficient in a less demanding environment, such as a production line. The communication protocol used to transmit data from the load cell to the data acquisition system can also affect accuracy and precision. Some protocols, such as Ethernet, offer high data rates and low latency, which can improve accuracy and precision. Others may have lower data rates and higher latency, which can degrade accuracy and precision.

STEP 3: DETERMINE APPLICATION MEASUREMENT RANGE AND RESOLUTION

The capacity and range of the load cell should be selected based on the maximum load that will be applied in the test environment. Select a sensor with a slightly higher capacity than the maximum expected load to allow for some margin of error. The communication protocol should be able to handle the data rate and resolution required for the load cell’s capacity and range.

STEP 4: ENVIRONMENTAL CONSIDERATIONS

The environmental conditions in the test environment, such as temperature, humidity, and vibration, can affect the load cell’s performance. Select a load cell rated for the specific environmental conditions in the test environment. The communication protocol should be robust enough to handle these conditions.

MAKING THE CONNECTION

DATA ACQUISITION USE CASE: Analog Connection to DAQ

COMPONENTS

• Sensor with analog output (mV/V, mA, V)
• DAQ connected to PC.
• Standalone or network integration

PLC OR SYSTEM INTEGRATION USE CASE: Digital Signal Conditioning

COMPONENTS

• Sensor
• Analog to Digital Converter (Wireless Transmitter)
• Digital Wireless Receiver (WTS-GW1) with Modbus-RS485 output
• Existing digital PLC

NETWORK INTEGRATION USE CASE: Connect to Existing Network

COMPONENTS

• Sensor
• Digital Signal Converter with Fieldbus (INF1)
• External Network, Existing Infrastructure
• Profinet, Ethernet IP, Ethernet TCP/IP, and others

EXTERNAL NETWORK: Connect to Your Network

COMPONENTS

• Sensor (Load Shackle shown)
• WTS-GW with Modbus RS-485
• Anybus Converter
• External Network
• Profinet, Ethernet IP, Ethernet TCP/IP, any network for which an Anybus converter exists

HIGH CHANNEL NETWORK USE CASE: Integrating Multiple Sensors to a Network

COMPONENTS

• Digital Signal Converter for Each Channel (BX8 with EtherCAT/CANbus)
• Multiple Sensors with Volume Channel Requirements
• External Network and Infrastructure
• Profinet, Ethernet IP, Ethernet TCP/IP

IO-LINK USE CASE: Cost-Effective and Network Agnostic

COMPONENTS

• IO-Link Sensors (of any type)
• IO-Link Hub for volume channel requirements
• Cost-effective industry-standard cabling
• External Network, Existing Infrastructure
• Used for internal cal data, hot swapping, and health monitoring

COMMUNICATION PROTOCOL TIPS AND CONSIDERATIONS

#1 DEFINE THE REQUIRED DATA RATE AND BANDWIDTH

Different sensors and instruments generate data at varying rates. Some may require high-speed, real-time data transmission, while others need lower bandwidth. Understanding the data volume and desired update frequency helps determine suitable protocols.

#2 UNDERSTAND PHYSICAL DISTANCE REQUIREMENTS BETWEEN THE DEVICES

The distance between sensors and instruments and the central control and monitoring system influences protocol choices.

#3 INVESTIGATE NOISE AND INTERFERENCE

Industrial environments can be rife with electromagnetic interference. Key considerations include shielded cables, error detection devices, correction mechanisms, and protocols inherently resistant to noise.

#4 DETERMINE THE ANALYSIS OF DATA AND SPEED OF OUTPUT

Some applications demand predictable and guaranteed message delivery times. Real-time control systems, for instance, rely on timely data exchange. Protocols with prioritization mechanisms and bounded latency, like CANbus or specific industrial Ethernet variants, might be necessary.

#5 EXAMINE EXISTING INFRASTRUCTURE AND COMPATIBILITY CONSTRAINTS

The communication protocol must be compatible with legacy equipment or specific hardware already in place. Upgrading existing systems to support a new protocol can be costly and time-consuming. Assessing compatibility with the existing infrastructure simplifies integration.

Review the recorded webinar for additional tips, references, and critical questions when investigating sensors and communication protocol options. Our team is also on hand to answer any questions.