Typical Signal Logic

An analog input is first scaled to the required engineering range. After that, alarm setpoints, hysteresis, texts, and logging are applied to the finished value.

The example below illustrates a typical level setup.

Figure: Typical analog input flow from scaling through alarms and data logging.

The example below illustrates how hysteresis prevents repeated alarms around the same threshold.

Figure: Hysteresis example that prevents repeated alarm changes around the same setpoint.

Transmitter Setup

Wire the transmitter before configuring signal type and scaling. See Analog Transmitter Wiring for 4-20 mA and 0-10 V wiring principles.

Signal Type

Select the electrical signal type that matches the connected transmitter output.

Measurement Range Minimum

Define the engineering value that corresponds to the low end of the input signal.

• Enter the real engineering value directly.
• For a 0..100 °C transmitter, set the minimum range value to 0.

Measurement Range Maximum

Define the engineering value that corresponds to the high end of the input signal.

• Enter the real engineering value directly.
• For a 0..100 °C transmitter, set the maximum range value to 100.

Signal Filtering

Filter Time

Use filter time to delay acceptance of a changed analog value until it has remained stable long enough.

• Use it when the raw signal is noisy.
• Longer times make the channel slower to accept brief signal changes.

Damping Value

Use damping value to smooth the analog signal across a percentage of the configured measurement range.

• 0 means no damping.
• Higher values give slower but more stable response.
• Example entry: use 50 for 5.0% of the measurement range.

Damping Time

Use damping time to define how fast the damping logic samples and updates the filtered value.

• 0 means constant sampling.
• Higher values increase the sampling interval.

Spike Size

Use spike size to reject sudden signal jumps that are larger than the accepted transient size.

• 0 disables spike filtering.
• Higher values allow larger transient jumps before rejection.

Spike Time

Use spike time together with spike size to define how long a spike may last before it is accepted as a real value change.

• Use it only when short electrical or sensor spikes are known to occur.
• Longer values make the filter more tolerant of brief transients before accepting them as real changes.

Signal Adjustment

Signal Proportionality

Use this setting to keep the scaled value standard or invert it across the configured range.

Linear Offset

Use linear offset to move the scaled value up or down by a fixed amount.

Density Correction

Use density correction when the analog value should be corrected by a proportional density factor rather than by a fixed shift.

• Example entry: use 1053 for a factor of 1.053.

Alarm Setpoints

Use the setpoints to define the LowLow, Low, High, and HighHigh alarm levels for the scaled value.

LowLow Minimum Limit

Use this limit for the most critical low alarm threshold.

• Example entry: use 100 for 10.0.

Low Minimum Limit

Use this limit for the normal low alarm threshold.

• Example entry: use 200 for 20.0.

High Maximum Limit

Use this limit for the normal high alarm threshold.

• Example entry: use 800 for 80.0.

HighHigh Maximum Limit

Use this limit for the most critical high alarm threshold.

• Example entry: use 900 for 90.0.

Hysteresis

Use hysteresis to avoid repeated alarm changes around the same setpoint.

• Example entry: use 5 for 0.5.

Alarm Texts

Use the alarm texts to define the operator-facing wording returned for the analog channel state.

• These texts are stored in a shared runtime text pool, so there is no fixed per-field character limit that can be documented honestly.
• Keep the text short, operational, and specific to the alarm condition.
• Leave the text empty when the installation does not need a dedicated message for that state.

LowLow Alarm Text

Use this text for the most critical low alarm message.

Low Alarm Text

Use this text for the normal low alarm message.

High Alarm Text

Use this text for the normal high alarm message.

HighHigh Alarm Text

Use this text for the most critical high alarm message.

Normal Text

Use this text when the analog channel returns to its normal state.

Report Through DataGuard

This page owns the analog source setup. If the scaled analog value must be logged in DataGuard or exported onward to Emiko, continue on DataGuard via Analog Inputs.

• Use the same channel number in the analog source setup and the DataGuard reporting setup.
• Configure signal type, measurement range, filtering, alarm limits, and names here before adding DataGuard reporting.

Best Practice

• Start with signal type and measurement range before setting alarm limits.
• Add alarm texts before expecting alarm messages.
• Enable DataGuard reporting only when the channel should produce history or data forwarding.
• Alarm limits and alarm texts only define channel behaviour. If the channel must send alarm messages to someone, configure the recipient groups separately on Shared Runtime Recipients and Notifications.