Contemporary-control-systems BASremote User Manual (firmware 3.1.x) Bedienungsanleitung PDF herunterladen (Seite 23)

TD040300-0MF

Figure 9 — Contact Closure Connections

For solid-state switches, there are further concerns. It is recommended that a solid-

state device have an opto-isolated open-collector NPN transistor output stage with a

collector-emitter output voltage (Vce) of at least 30 V. Output sinking current should be

greater than 5 mA. The collector-emitter saturation voltage should be less than 0.2 V

when sinking 2 mA. The emitter should be connected to point B and the collector to

point A which is the more positive point. This polarity must be observed when using

solid-state devices. When an input is configured for a contact closure, the BAS Remote

sets the low-threshold to 2 V and the high-threshold to 3 V. When a contact is made or

the solid-state switch is on (resulting in a saturated output), the voltage at point A is

close to zero volts. The corresponding LED for that channel will be on. If the contact is

opened or the solid-state switch is turned off, the voltage at point B will quickly begin to

rise towards 24 V. Once the voltage passes the 3 V high-threshold, the input channel

will sense the “off” state. To return to the “on” state, this voltage needs to return to 2 V.

The one-volt difference is called hysteresis. There is no need to add an external pull-up

resistor when using a contact closure input.

Contact closure inputs are sampled every 10 ms and for a change of state to be

recognized, the input state must be stable for two consecutive samples. Therefore,

contact closure response is from 20–30 ms.

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Contemporary-control-systems BASremote User Manual (firmware 3.1.x) Bedienungsanleitung Seite 23