IO module replacement advice: Check shielding, ground loops, electromagnetic noise

I/O wiring can be among the most challenging (and perhaps feared) of upgrades. When replacing input/output connections, what are key considerations? John Lehman, Dataforth Corp. engineering manager, offered answers to some key questions.

10/20/2011


Twisted wire pairs reduce magnetically induced errors. Courtesy: DataforthControl Engineering: When replacing input/output connections, what are key considerations?

John Lehman, Dataforth Corp. engineering manager: When replacing input/output connections, key considerations are grounding, shielding, use of twisted pair cables, cable spacing, bundling of signal and power conductors, appropriate wire gauge, insulation rating, proper wire routing techniques, hazardous location concerns, and wiring practices for system electromagnetic compliance.

Q: Is there documentation?

Lehman: Good installations and system designs will have thorough documentation on I/O connection and wiring requirements. Dataforth offers extensive information on I/O wiring to preserve signal integrity in a signal conditioning tutorial. https://www.dataforth.com/catalog/pdf/DTF-Tutorial.pdf 

Q: What functionality do attached applications need to incorporate?

Lehman: The functionality that attached applications need to incorporate depends on system requirements. Using isolated signal conditioning products relaxes the many requirements of I/O wiring and solves many system wiring problems.

Q: What types of signals (analog, digital, serial, mixed...), what units (current, volts, resistance, ac, dc...), what range, and how many channels are needed?

Lehman: These are all important considerations for I/O wiring and are dictated by system requirements. Analog signals, digital signals, and power signals should be routed in separate bundles, or at least in separate twisted, shielded pair cables to preserve signal integrity. Channel input-to-output isolation, input-to-power isolation, and channel-to-channel isolation are also critical specifications of a good system design.

Q: What network protocols are required, and will they be wired, wireless, serial, digital, or a combination?

Lehman: The most common networking method remains TCP/IP. Modbus is still a prevalent and useful protocol. Wireless is making inroads into many industrial applications. Q: What are the sensing, signal conditioning, distributed control, isolation, and other requirements? Lehman: Modern sensors allow users to monitor more process variables than ever, which improves process efficiency and reliability and provides for better health-of-machine statistics, as well as prevention of downtime and accidents. Signal conditioning is an essential part of any system design as it provides proper scaling, filtering, linearization, and isolation. Microcontrollers, miniaturization of electronics, and wired and wireless networks allow more distributed control than ever. This expanded control, along with new opportunities in remote process monitoring, also supports more efficient, reliable, safe, and cost-effective systems.

Q: Will the application expand, and by how much?

Lehman: Good I/O wiring practices allow for easier future expansion.

Q: What design and how granular should the modules be?

Lehman: I/O wiring is an essential part of any successful system design and must be considered from the start of a project. Large systems, once wired, can be prohibitive to reconfigure.

Q: Will the I/O connections be enclosed or exposed?

Lehman: System requirements will specify whether I/O connections are enclosed or exposed. This is largely an environmental concern, but it is also important for operator safety and for applications in hazardous locations where arcing and sparking are not allowed.

Q: What are among the most-overlooked considerations?

Lehman: The most overlooked considerations are grounding, shielding, ground loops, capacitively and inductively coupled noise, and wiring practices for electromagnetic compliance (CE, FCC).

- Mark T. Hoske, CFE Media, Control Engineering, www.controleng.com, and John Lehman, engineering manager at Dataforth Corporation. www.dataforth.com



Engineers' Choice Awards
The Engineers' Choice Awards highlight some of the best new control, instrumentation and automation products as chosen by Control Engineering subscribers.
System Integrator Giants
The System Integrator Giants program lists the top 100 system integrators among companies listed in CFE Media's Global System Integrator Database.
System Integrator of the Year
Each year, a panel of Control Engineering and Plant Engineering editors and industry expert judges select the System Integrator of the Year Award winners in three categories.
Design of Safe and Reliable Hydraulic Systems for Subsea Applications
This eGuide explains how the operation of hydraulic systems for subsea applications requires the user to consider additional aspects because of the unique conditions that apply to the setting
How to Maximize Factory Automation Efficiency with Low Cost Machine Vision
This eGuide illustrates solutions, applications and benefits of machine vision systems.
Wireless Reliability in Harsh Environments
Learn how to increase device reliability in harsh environments and decrease unplanned system downtime.
October 2018
HMI hardware evolution, Data acquisition strategies, Matching motors and drives, Machine vision advice
September 2018
Optimize controls via cloud software, ladder logic simulation, industrial wireless best practices
August 2018
Augmented reality and virtual reality education, autotuning PID control, cybersecurity advice, educating engineers
Edge Computing
This article collection contains several articles on how today's technologies heap benefits onto an edge-computing architecture such as faster computing, better networking, more memory, smarter analytics, cloud-based intelligence, and lower costs.
Data Center Design
Data centers, data closets, edge and cloud computing, co-location facilities, and similar topics are among the fastest-changing in the industry.
IIoT: Machines, Equipment, & Asset Management
Articles in this digital report highlight technologies that enable Industrial Internet of Things, IIoT-related products and strategies.
SIDB

Find and connect with the most suitable service provider for your unique application. Start searching the Global System Integrator Database Now!

October 2018
2018 Product of the Year; Subsurface data methodologies; Digital twins; Well lifecycle data
August 2018
SCADA standardization, capital expenditures, data-driven drilling and execution
June 2018
Machine learning, produced water benefits, progressive cavity pumps
John O. Ayuk, PE, CFSE, PMP, CAP
Automation Engineer; Wood Group
Doug Baker
System Integrator; Cross Integrated Systems Group
Jose S. Vasquez, Jr.
Jose S. Vasquez, Jr.
Fire & Life Safety Engineer; Technip USA Inc.
Data Centers: Impacts of Climate and Cooling Technology
This course focuses on climate analysis, appropriateness of cooling system selection, and combining cooling systems.
Safety First: Arc Flash 101
This course will help identify and reveal electrical hazards and identify the solutions to implementing and maintaining a safe work environment.
Critical Power: Hospital Electrical Systems
This course explains how maintaining power and communication systems through emergency power-generation systems is critical.
Engineers' Choice Awards
The Engineers' Choice Awards highlight some of the best new control, instrumentation and automation products as chosen by Control Engineering subscribers.
System Integrator Giants
The System Integrator Giants program lists the top 100 system integrators among companies listed in CFE Media's Global System Integrator Database.
System Integrator of the Year
Each year, a panel of Control Engineering and Plant Engineering editors and industry expert judges select the System Integrator of the Year Award winners in three categories.
Design of Safe and Reliable Hydraulic Systems for Subsea Applications
This eGuide explains how the operation of hydraulic systems for subsea applications requires the user to consider additional aspects because of the unique conditions that apply to the setting
How to Maximize Factory Automation Efficiency with Low Cost Machine Vision
This eGuide illustrates solutions, applications and benefits of machine vision systems.
Wireless Reliability in Harsh Environments
Learn how to increase device reliability in harsh environments and decrease unplanned system downtime.
October 2018
HMI hardware evolution, Data acquisition strategies, Matching motors and drives, Machine vision advice
September 2018
Optimize controls via cloud software, ladder logic simulation, industrial wireless best practices
August 2018
Augmented reality and virtual reality education, autotuning PID control, cybersecurity advice, educating engineers
Edge Computing
This article collection contains several articles on how today's technologies heap benefits onto an edge-computing architecture such as faster computing, better networking, more memory, smarter analytics, cloud-based intelligence, and lower costs.
Data Center Design
Data centers, data closets, edge and cloud computing, co-location facilities, and similar topics are among the fastest-changing in the industry.
IIoT: Machines, Equipment, & Asset Management
Articles in this digital report highlight technologies that enable Industrial Internet of Things, IIoT-related products and strategies.
SIDB

Find and connect with the most suitable service provider for your unique application. Start searching the Global System Integrator Database Now!

October 2018
2018 Product of the Year; Subsurface data methodologies; Digital twins; Well lifecycle data
August 2018
SCADA standardization, capital expenditures, data-driven drilling and execution
June 2018
Machine learning, produced water benefits, progressive cavity pumps
John O. Ayuk, PE, CFSE, PMP, CAP
Automation Engineer; Wood Group
Doug Baker
System Integrator; Cross Integrated Systems Group
Jose S. Vasquez, Jr.
Jose S. Vasquez, Jr.
Fire & Life Safety Engineer; Technip USA Inc.
Data Centers: Impacts of Climate and Cooling Technology
This course focuses on climate analysis, appropriateness of cooling system selection, and combining cooling systems.
Safety First: Arc Flash 101
This course will help identify and reveal electrical hazards and identify the solutions to implementing and maintaining a safe work environment.
Critical Power: Hospital Electrical Systems
This course explains how maintaining power and communication systems through emergency power-generation systems is critical.
Engineers' Choice Awards
The Engineers' Choice Awards highlight some of the best new control, instrumentation and automation products as chosen by Control Engineering subscribers.
System Integrator Giants
The System Integrator Giants program lists the top 100 system integrators among companies listed in CFE Media's Global System Integrator Database.
System Integrator of the Year
Each year, a panel of Control Engineering and Plant Engineering editors and industry expert judges select the System Integrator of the Year Award winners in three categories.
Design of Safe and Reliable Hydraulic Systems for Subsea Applications
This eGuide explains how the operation of hydraulic systems for subsea applications requires the user to consider additional aspects because of the unique conditions that apply to the setting
How to Maximize Factory Automation Efficiency with Low Cost Machine Vision
This eGuide illustrates solutions, applications and benefits of machine vision systems.
Wireless Reliability in Harsh Environments
Learn how to increase device reliability in harsh environments and decrease unplanned system downtime.
October 2018
HMI hardware evolution, Data acquisition strategies, Matching motors and drives, Machine vision advice
September 2018
Optimize controls via cloud software, ladder logic simulation, industrial wireless best practices
August 2018
Augmented reality and virtual reality education, autotuning PID control, cybersecurity advice, educating engineers
Edge Computing
This article collection contains several articles on how today's technologies heap benefits onto an edge-computing architecture such as faster computing, better networking, more memory, smarter analytics, cloud-based intelligence, and lower costs.
Data Center Design
Data centers, data closets, edge and cloud computing, co-location facilities, and similar topics are among the fastest-changing in the industry.
IIoT: Machines, Equipment, & Asset Management
Articles in this digital report highlight technologies that enable Industrial Internet of Things, IIoT-related products and strategies.
SIDB

Find and connect with the most suitable service provider for your unique application. Start searching the Global System Integrator Database Now!

October 2018
2018 Product of the Year; Subsurface data methodologies; Digital twins; Well lifecycle data
August 2018
SCADA standardization, capital expenditures, data-driven drilling and execution
June 2018
Machine learning, produced water benefits, progressive cavity pumps
John O. Ayuk, PE, CFSE, PMP, CAP
Automation Engineer; Wood Group
Doug Baker
System Integrator; Cross Integrated Systems Group
Jose S. Vasquez, Jr.
Jose S. Vasquez, Jr.
Fire & Life Safety Engineer; Technip USA Inc.
Data Centers: Impacts of Climate and Cooling Technology
This course focuses on climate analysis, appropriateness of cooling system selection, and combining cooling systems.
Safety First: Arc Flash 101
This course will help identify and reveal electrical hazards and identify the solutions to implementing and maintaining a safe work environment.
Critical Power: Hospital Electrical Systems
This course explains how maintaining power and communication systems through emergency power-generation systems is critical.
click me