Can you please tell me what the input impedanceof the WebBrick DIs with pull-up resistance is? Reason for asking is we want to connect a PIR with high analogue output impedance (100 microA at 5V) to a DI and it doesn't work. Works on analogue though.

The digital inputs 0 to 7 have a weak pullup of circa 50K, the PIR needs to be able to pull the input down. 100uA at 5V is 50K. So not surprised. Can you link to the sensor data sheet?

The pullup on digital inputs 8 to 11 may be lower.

Can the PIR sink 50uA when its output is low?

L.
 

 Hi Thanks for the response. The sensor is a PANASONIC EW AMN12111.

We have tried it on DIs 8 to 11 but with no more luck. I seem to remember someone saying it has a ttl output. This is not the case for this model. The sensor works fine using an analogue input and it works even better with 4 analogue inputs connected in parallel due to the increased sampling rate. When you increase the sample rate on each input with the revised firmware that will make the job even easier.

 
Regards

 
Chris 

Looked at the dataheet and the device is an active drive to 5V and open circuit otherwise. You could use a simple transistor  to invert it. i.e BC108 or modern equivalent.