Workstation Activity Sensor Solutions

Signals From Each Workstation

A cornerstone of the Ecogate solution is to provide exhaust ventilation only to machines that are currently while closing the gates at inactive machines.

In a woodworking application, this means only the machines actively making sawdust have their gates open while the other gates remain closed.

To do that Ecogate needs to read the signal from each workstation indicating that the workstation requires ventilation (or dust collection). This signal is connected to the Ecogate gate sensor input.

(Technical detail: the sensor input at the gate has two wires with 24 V DC; when these two wires are connected by external contact (current is about 10 mA) the gate will open. Do not connect any external voltage to this sensor input! All that is needed from a workstation is the dry contact (relay output) or, if the workstation does not have one, use one of the sensors recommended by Ecogate.)

Here are the options to obtain dry contact at various workstations.

Best Solution – Dry Contact “Ventilation Request” Provided by Manufacturer of the Machine

An example of this ideal approach was when Andersen Windows purchased machines for expanding their facilities in Minnesota and Wisconsin. They specified when they ordered the new machinery that they should be equipped with a dry contact to trigger an Ecogate gate. This is ideal because the manufacturer perfectly understands the functions of the machine and can close the dry contact a few seconds ahead of the time when the machine needs ventilation. In that way, the gate has enough time to be fully open at a time when dust collecting is necessary. This approach requires minimum time during installation; therefore it is very cost-effective.

A similar approach was used during our installation at Ikea: Ikea contacted manufacturers of the equipment requesting a software update that would include the dry contact output (of the PLC) for Ecogate. A disadvantage of this approach is that the response time from manufactures is relatively slow (compared to when you specify output for an Ecogate system at a time of order).

New Schelling CNC saw: orange wires are dry contact prepared for Ecogate

Another slight modification to this option was when Rubbermaid in Missouri installed a new Schelling CNC saw. We just asked engineers from the manufacturer commissioning for a new saw to create a dry contact for Ecogate. This request was easily fulfilled: the dry contact was wired, and proper timing programmed in the control PLC of the saw.

Second Best Solution - Custom PLC Programming

Many machines are using a PLC to control their functionality. Some PLC programming for custom machines is programmed directly by factory maintenance engineers. This is ideal because they can add the functionality of the dry contact output for Ecogate to their program. A similar situation is if a manufacturer programs the machine PLC, but factory engineers have the PLC source code, and thus are able to modify it – again this provides the best possible signal. This approach requires some time to modify the PLC software. We used this option for example at Andersen Windows, at Rubbermaid, and at other factories.

Third Option: The VOLT or CURRENT Sensor, or DRY CONTACT

If the above options are not available, Ecogate will setup workstation activity sensors during system installation. This is a very common approach in many typical system installations.

To understand correctly the machine function, the Ecogate Chief electrician will need help from local maintenance: they will walk-through factory, machine by machine, and determine to what circuit the sensors can be connected. Ideally, it will be a circuit that is active before ventilation is required. For example, on a CNC saw it will be the circuit that activates an arm holding material to be cut because this circuit is active before the saw starts cutting.

What sensor is necessary? If the dry contact is available or can be added as an option to the contactor (most contactors allow to attach optional dry contact), then a sensor is not necessary and the contact can be just wired to the gate sensor input.

If the dry contact is not available, we can use either Ecogate AC-DC VOLT or AC VOLT sensor or current sensor. You can read more about sensors offered by Ecogate here.

Options Available in greenBOX Software

Normally Open/ Normally Closed Logic

The Input logic can be set from Normally Open (NO) to Normally Closed (NC).

Input Timer

If a signal is active for a very short period (for example 0.1 sec), but we will need to keep the gate open for a longer time, we can use the Input Timer function.

Off Delay

For each gate separately we can program OFF DELAY time: the gate will not close immediately after the signal from the workstation is not active, but with set delay.

Keep Gate Open

This is typically used if the sensor is not yet installed or if the sensor is not working; this option will keep the gate open until the sensor will be repaired or installed.

Open Gate only if Sensor is Active

The meaning of this option is that the gate will not be used for minimal airflow. This is typically used for all sanders, as it is not acceptable to open the gate and start ventilation if the operator is changing the sanding belt (a vacuum will make it difficult or impossible to remove and reinstall the belt).

Author: Ales Litomisky

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