Question concerning supervised input

[donstephens]

I just ordered an Applied Digital SECU-16I and have a question concerning 'supervised input'. The online manual has a schematic of a SECU-16I, as can be seen at http://www.appdig.com/adicon_new/manuals/secu16i.pdf page 2, that has a 1K ohm resistor across the two legs of the input. My question is this: Do I need the resistor across each input or can I use one resistor on the common?

Thanks

[Michael McSharry]

For each digital input (on/off) you want a resistor between its input and the common. This biases the voltage to a midpoint so if the input being sensed is disconnected (e.g. wire breaks) the "supervised" function will be able to detect it. If you are using the input as a 0-5V analog input then the resistor is not used.