ML-OO-SW – Option board

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Adds three galvanic isolated switches with potential free contacts

An ML-417 data logger is standard provided with one digital output, an open collector alarm output to switch on an actuator/relay in case a parameter value is outside its limits (e.g. a high water level).

You can use the ML-OO-SW board to add three more digital outputs, in case you need more than one digital output or want to switch on an actuator/relay to prevent an alarm situation (e.g. to switch on a gasoline generator as backup for a solar or wind turbine powered installation to avoid a power outage).

Additional information

About these switches

The three switches are galvanic isolated from the ML-417 as well as from each other. The switches have potential free contacts and therefore acting like ordinary wired switches. The switches don’t need a voltage to operate and they don’t have a positive or negative terminal, so you could switch on a DC as well as an AC circuitry as long as the connected voltage does not exceed ±100V and the current through the contacts does not exceed ±200mA.

Specifications

  • Switches: 3
  • Protection: Galvanic isolated
  • Contacts: Potential free
  • Connected voltage: 100V maximum
  • Contact current: 200mA maximum
  • 15uA quiescent current

Operation

The ML-417 can be configured to regularly, e.g. after a sensor reading session, update the state of the switches.

  • A switch contact is made when the value of the correlated data logger parameter equals or exceeds 0.7 and released when it equals or falls below 0.3
  • The best way to actuate switches is by using calculated channels evaluating to 0 or 1 (See: example)
  • Only values of parameters, up to 3, with their “data output flags” set to the auxiliary output board will be used for updating the state of the switches.
  • The value of the first parameter will be correlated to the first switch and so on, the order of parameters can be organized through the “Parameter overview”-menu of the ML-417.

Example

Assume you have:

  • An irrigation pond that can be replenished by natural sources (e.g. rain) or a paid source and you want to avoid reaching a critical level and paying to much.
  • The critical LEVEL of the pond is 2m and the conditional replenish level 2.5m
  • The supply pump capacity is 4m3/h
  • You only want to use the paid source:
    • When the pond reaches its critical level or
    • When the pond reaches the replenish level and the 24h rolling average of the irrigation FLOW exceeds 2m3/h (50% of the pump capacity).

Steps to take:

  • Use an aggregated channel to evaluate FLOWAVG from FLOW by specifying an aggregation period of 86400 seconds
  • Use a calculated channel that evaluates FLOWAVG and LEVEL to 1 in case the supply pump should be switched on and 0 when it should be switched off
  • Correlate and order the calculated channel to a switch by setting its “data output flags” to the auxiliary output board

Formula: le(:LEVEL;2.0;1;le(:LEVEL;2.5;ge(:FLOWAVG;2.0;1;0);0))

Explanation:

  • If :LEVEL lower than or equals (le) 2m return 1 to start the pump
  • If :LEVEL lower than or equals (le) 2.5m check the flow, else return 0 to stop the pump
  • If :FLOW greater than or equals (gt) 2m3/h then return 1 to start the pump, else return 0 to stop the pump

Discover the possibilities

Want to know more about what YDOC can do to help you with your quest for the right data logger? Do not hesitate to get in contact.

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