nSP5 2P LVR: How Does The nSP5 2P LVR Work?

Louver Control

The goal of this product is to provide closed loop photocell control that maintains a set-point (in foot candles) at the sensor by using both a louver (used to block the sun) and a set of dimmable electric lights.

This brought about the need for two new devices, nSP5-2P-LVR and nCMR-ADC-LVR. The nCMR-ADC-LVR has the set-point and the nSP5-2P-LVR responds to commands from the nCMR-ADC-LVR.

The nSP5-2P-LVR will be defaulted to “Follow Photocell Mode” = ON and the nCMR-ADC-LVR will be defaulted to “Photocell Transition Time” of 45 seconds for both On and Off.


While in “Follow Photocell Mode”, the louver will open and close in settable increments/pulses to maintain the closed loop set-point. There is a setting for pulse duration and delay in-between pulses in response to the photocell. The main rule to remember is the louver must be fully open (max light passing through) before the electric lights turn ON. Once the electric lights turn ON, it behaves just like a regular nCMR-ADC and will increment or decrement the electric light level to maintain the set-point.

In the video below, you will see when I turn up the simulated sun-light, the louver starts to close. When I turn down the simulated sun-light, the louver starts to open.

When it is in this mode, the louver will stop moving when the light level reaches 10% of the set-point on either side.

The auto set-point still works as normal and will set the set-point to the amount of light the electric lights add to the space. The louver will remain constant during the auto set-point procedure so as to not affect the measurements.

The sunlight discount factor still works as normal where when the electric lights are OFF, it acts as a multiplier to the set-point in the same way a nCMR-PC, but when the electric lights are ON it divides the sunlight’s contribution the same way as a normal nCMR-PC-ADC.


The louver responds to switch up and down commands with similar pulses. There is a different setting for pulse duration and delay in-between pulses in response to switches. If the electric lights are OFF and the user is holding the Up button, the louver will Open incrementally until fully open, and then the photocell will turn ON the electric lights and increment them Up as normal. If the user is holding the Down button, the photocell will decrement the electric lights until they reach minimum, and then will start to close the louver. At any time the user can let go, and after 5 seconds the photocell will get a new set-point.

The louver and photocell respond to switch ON commands by fully opening the louver and turning the electric lights to full bright and to switch Off commands by fully closing the louver and turning Off the electric lights.


If the louver is tracking occupancy, it will fully close when timed out, and fully open when re-tripped.


The louver can be forced to either Open fully or Close fully by setting it to “Override ON” and “Override OFF” respectively. If the louver is set to “Override OFF”, it will close fully and therefore since the photocell will see that it is not fully open, the electric lights will also be inhibited. If this is undesired, the user must also override the electric lights ON with a normal override setting.

Louver Positioner

If the user just wants a louver positioner, they must disable the “Follow Photocell Mode” and the louver will follow switch increments and stay there. Currently there is no way to go to an absolute position (since there is no feedback from the louver).

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