Metering Inputs Menu Explained (Cortex series)

Metering (Analog) Inputs

The Metering inputs are used to process and measure analog signals. They are bipolar, differential inputs with common-mode rejection of up to 80V. They can be configured for signal detection (pseudo RMS) an also for 4-20mA modes.

Please see this article for details about the generic Main screen, Description screen and Vocal Description screen.

1 – ID: ID of the selected input. Select from the drop-down menu.

2 – I/O DESCRIPTION RETRIEVAL: Click to retrieve and display the current normal description of that ID. Normally hidden to minimize data transfers on low speed or high fee data connections.

3 – QUALIFIER: Qualifying element (operand) which can be any input, output, flag, timer, SNMP GET, Logic Gate, etc. Essentially any ID in the Cortex can be used to mute or unmute the input to prevent it from taking any action. When the Qualifier is active, the input will be monitored and be able to generate alarms. When the qualifier is non-active (or normal), the input will be muted and it will not be able to generate an alarm. To invert the Qualifier’s level, simply put a ! in front of its ID. For example, use !1D01 to invert it. Leave the Qualifier field blank for a “don’t care” condition.

4 – VOLTAGE RANGE: Voltage measuring range of the input. Select a range value which is higher than the maximum voltage expected on the input. If the input voltage exceeds this value, saturation or signa clipping will occur. On the other hand, be sure to use a range that is not too high because signal resolution will be lost.

5 – NORMAL VALUE: Expected normal operating value for the input. During operation, a user can click on the corresponding input’s meter or display box and this value will appear.

6 – DEFAULT VALUE: For inputs from MEXM (Expansion) units only. Default value that the input will take if the Cortex loses communications with the MEXM.

7 – MEASUREMENT UNIT: Select desired measurement unit, or enter your own. Maximum of 3 characters.

8 – AUTOMATIC LIMIT CHANGE QUALIFIER: ID of an input that will trigger a limit change condition. For example, if a site has a backup transmitter with 50% of the power of a main transmitter, and ID 1D01 indicates that the site is now operating on the backup^, then this condition will trigger the application of the Change Multiplier (next item below).

9 – AUTOMATIC LIMIT CHANGE MULTIPLIER: In the example above, the multiplier would be 0.5. This factor is automatically applied to all the alarm limits set in this Metering input, thereby saving the user the trouble of having to go through all the limits and adjusting them for the new, lower, power. Very useful to reduce the number of false or nuisance alarms, while still being in full control of the transmission site. Multiplier can be any number between 0 and 9999.

10 – DELAY BEFORE ACTION: Delay before the input changes into an active state when an out-of-limit condition occurs. Prevents glitches from setting-off any alarms.

11 – DELAY BEFORE RETURN TO NORMAL: Delay before the input returns to a normal state once an out-of-limit condition is over. Prevents too-brief returns-to-normal from causing multiple repeated alarms.

12 – LEVEL 1: Close / open the Level 1 menu. Metering inputs can be set up with 2 alarm levels. Typically a minor alarm for when a level drops slightly and then a major alarm when it drops significantly.

13 – ACTION TYPE: Selects the action type that will happen when an out-of-limit condition occurs. 3 types are available: Major alarm, Minor alarm, and Command (CMD). On CMD, no alarm will be triggered. Use this Action when you want to take actions without triggering any alarms.

14 – LOW LIMIT: Voltage value below which the input state will switch from normal to active. * is a “don’t care” condition.

15 – HIGH LIMIT: Voltage value above which the input state will switch from normal to active. * is a “don’t care” condition.

16 – CONTROLLED OUTPUT: Outputs to be controlled (on/off) based on the state of this input. The two output types allowed are relays (both physical and virtual) and SNMP SETs. For the relays, adding a P suffix will Pulse the relay (ex: 1R01P), L will Latch it and R will Release it.

17 – LEVEL 2: Open / close the Level 2 menu. Same as Level 1.

18 – ENABLE: Enable / disable the input. Useful to deactivate an input, without losing all its settings, when the input is causing intermittent problems or nuisance alarms

19 – QUALIFIER – STATE or DATA: STATE (default setting): the State (Normal or Active) of the input being qualified can change only when the Qualifier is active. Readings from the input (Current Value) continue to be updated periodically independently from the Qualifier state. DATA: Same as the STATE mode, but in this case the readings from the input (Current Value) remain frozen at their latest values, as long as the Qualifier is not active. This mode is used like a “Sample-and-Hold” for the readings from the input.

20 – SENSOR COEFFICIENTS: Virtual curve-fitting feature that allows compensation for gain, offset, inversion and even 2nd-order non-linearity of input sensors. A is the 2nd-order compensation, B is the gain (and inversion) while C is the offset. When D is 1, then a base 10 Log is applied to calculate decibels. Default values are A=0, B=1, C=0 and D=0, giving a direct 1 to 1 relation between the measured voltage or current and the sensor’s output. Davicom has a sensor curve fitting utility Excel file that can help you calculate the required coefficients. Please contact Davicom’s technical support department for more information on how to obtain and use this file.

21 – SIGNALLING ON – ALARM: Enables / disables alarming. When checked, any out-of-limit condition will automatically generate an alarm. When unchecked, no alarm will be triggered when an out-of-limit condition occurs.

22 – SIGNALLING ON – RETURN TO NORMAL: Enables / disables Return To Normal signalling. When checked, a notification will be generated when the input changes back to its normal state after an out-of-limit alarm condition. When unchecked, no notification will be sent when the initial alarm condition returns to normal.

23 – SYSTEM LOG: Log the input’s activity in the System Log. Useful when inputs do not need to be logged, but are required for day-to-day operation.

24 – HYSTERESIS – LOW LIMIT: Gap value which must be exceeded, when the input voltage returns from a low out-of-range state, before the input can actually switch back to a normal state.

25 – HYSTERESIS – HIGH LIMIT: Gap value which must be exceeded, when the input voltage returns from a high out-of-range state, before the input can actually switch back to a normal state.

26 – REFRESH / READ: Refresh / read the screen content.

27 – SAVE / WRITE: Save the screen content.

28 – EXIT: Exit menu.

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