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KB53389
Downloading and starting an ioControl strategy with PIDs on Ethernet-based I/O units, may cause outputs to spike
Revision:  2.0
Published:  9/5/2006
Applies To
Firmware for:
SNAP-PAC-R1
SNAP-PAC-R2
SNAP-UP1-ADS
SNAP-UP1-M64
SNAP-B3000-ENET
Versions
Behavior is present in version:  
R7.1a

SYMPTOMS

A PID output with a host-based setpoint on Ethernet-based I/O units, may spike when a just-downloaded ioControl strategy is started. The spike occurs while the strategy goes through the Init_IO (initialize I/O) chart.

CAUSE

The spike may occur as a just started strategy transitions from its initial setpoint from host value (default value is 0), to the value set by the running strategy. In a PID where a lower setpoint indicates the output should increase, the setpoint temporarily going to zero would cause the output to go high in an effort to bring down the process variable. This would appear as a spike in the output.

WORKAROUND

In the ioControl Configurator Add PID Loop dialog, configure the Initial Value for the Setpoint from Host to its most common operating value. By doing so, there will be little or no spike when the strategy transitions form its initial starting value to the value set by the running strategy.

RESOLUTION

Opto 22 is aware of this issue.

Relevant Downloads
No relevant downloads have been specified.
Questions? Contact Opto 22 Product Support.
Phone: 800-835-6786 or 951-695-3080
Email: support@opto22.com

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