Quote:
Originally posted by dave_l
I *REALLY* want access to the Switch 1/2/3 LEDs on the operator interface.
I have _some_ electronics knowledge, and suspected that the DIs are open collector inputs with a pull up resistor.
I am wondering how involved it would be to use say an NPN (ie current sinking) switching transistor with one of the relay outputs to switch one of the digital inputs?
If possible, I would then use some of my unused relay outputs to control DI 1/2/3 and hence the three LEDs on the OI.
Can any electronics gurus out there suggest a simple circuit?
Thanks
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The OI Manual (.pdf from IFI) says that the switch LEDs represent the switch inputs on the RC and are not programmable in PBASIC.
On the other hand, if you used sw1 for the input from your pressure switch, for determining when the compressor should be turned on, you could see from the sw1 LED when the compressor was drawing the battery voltage down.
The "relay outputs" that show up on the OI are the signal the RC passed back to the OI. This same pair of bytes (RelayA and Relay B) are passed inside the RC to the bank of output circuits which control the relay outputs. Shorting one of these would short an output, but have no effect on the feedback bytes, nor on the LEDs. If you wish to use the relay LEDs, you'll have to use Relay1_fwd = 1, or Relay2_rev = 0, to do it
Have you thought of utilizing Out8,9,10 & 11 ? These are low-current outputs to drive your LEDs, and are available from Port1.
dave_l :
Yes just an OC NPN transistor, collector to the input, emitter to ground. Biasing in a digital connection is optional. Every RC digital input has a 10k pull-down resistor to +5V, and all the series resistance it wants, internally. for the sake of your transistor, some series resistance in the base circuit is recommended.
See the IFI site for a .pdf file of the equivalent input circuit.
This is the kind of output you have with the Banner sensors (discussed elsewhere on CD).