Valve controller adds diagnostics capabilities to reduce downtime, extend versatility

Diagnostics capabilities allow valves to warn of problems prior to failures.
By Control Engineering Staff December 18, 2008

Stonel has announced a new on-board diagnostics system for its Axiom AMI96 discrete valve communication and control device. The capabilities can help reduce process downtime and maintenance costs.

The system communicates via an AS-i network to save on wiring and installation costs. The company says the new system is an optional upgrade that can be added to the valve controller, and provides several local and remote diagnostic alerts to warn personnel of any impending trouble with the valve, actuator, or the valve communication and control terminal (VCT). Alerts may be triggered by a drop in pneumatic supply pressure below operational levels, or when a shorted or opened solenoid circuit is detected. Should the VCT’s pneumatic spool or pilot valve become stuck due to air line contamination or others causes, or if the automated valve stalls in mid-stroke due to a jammed valve or actuator, additional alerts are activated. Alerts are cleared automatically as soon as normal operating conditions are restored.

Using the VCT’s intelligent communication capabilities, open and closed settings can be initiated using on-board push buttons, or remotely from a control station. Also, the automated valve’s location can be confirmed by remotely initiating a “wink” function, which flashes on-board LEDs for clear identification without interrupting valve operation.

The AS-Interface protocol (version 2.1 or greater) allows up to 31 Axiom VCTs to be networked into the control system on a single two-wire cable. Communication bits for position status, control and diagnostics may be mapped into standard DCS or PLC systems without special software.

—Edited by Peter Welander, process industries editor, PWelander@cfemedia.com ,
Control Engineering Process Instrumentation & Sensors Monthly
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