Rockwell Automation Upgrades Analog Safety I/O Modules to Meet Fail-safe Requirements

February 06, 2022 by Seth Price

Rockwell Automation introduced several new additions to their Flex 5000 line for improved fail-safe measures.

Rockwell Automation released new analog input/output (I/O) modules to enhance safety on the shop floor. The newest members of the Allen-Bradley Flex 5000 I/O module series meet several industry benchmarks for fail-safe operation and integrate easily with existing Rockwell Automation hardware and software.


What are Analog Safety I/O Modules?

Safety I/O modules receive data from emergency stop buttons, light curtains, sensors, and interlocks. They also can send control signals to stop machinery, sound alarms, record data, and trigger emergency response equipment. 

Safety Control Devices

Various safety input devices. Image used courtesy of Rockwell Automation


Much like the human nervous system, they can trigger actions faster than sending data to a central processing unit (CPU) somewhere else in the plant. If you touch a hot stove, reflexes withdraw your hand, rather than waiting for the signal to reach your brain, then have your brain send a signal to your hand to move. 

Similarly, if a light curtain is breached near a fast-moving machine, the local safety I/O module can stop the machine’s motion faster (on the order of a few to tens of milliseconds) than sending the signal to a computer elsewhere and waiting for it to send the control signal to the machine.

Besides directly stopping equipment, the modules can also manage processes, such as burner control for heating a boiler, turbine speed control, and compressor duty cycle, where the incoming signal may not be a simple boolean (on/off). Instead, the process variable might be the natural gas flow rate and the control signal may be to alter the position of a valve, with the added backup that an emergency condition will quickly close the valve.


What’s New?

These new Flex 5000 modules are an update of previous models, with enhanced communication capability, with 1 Gb EtherNet capability along copper wire or fiber. They can be arranged in common topologies, such as rings, stars, lines, or redundant parallel systems. 


FLEX-5000 Remote Safety IO System

Allen-Bradley Flex 5000 Series controllers and I/O modules. Image used courtesy of Rockwell Automation

The updated modules are designed to meet SC 3 (SIL 2 and SIL 3), TÜV certified up to SIL 3, PLe, Cat. 4, fail-safe protocols. This means response times of up to 10 ms. They can be easily interfaced on existing Series 5000 hardware, mounting in the same chassis, and communicating with the same Studio Logix Designer 5000 software.

The Flex 5000 series modules are built to withstand harsh environments, such as temperature extremes (-40 ℃ to 70 ℃ during operation), vibration, moisture, dust, and so on. They can be supplied with an optional chemical-resistant coating that will protect the modules from occasional chemical droplets and mist. 

In the process safety world, engineering controls are among the most effective safety measures. Instead of relying on standard operating procedures (SOPs) and other administrative controls for safety purposes, an engineered solution is available. The new line of Series 5000 Analog Safety I/O modules is one such engineering control.