many thanks.
Found this is in the doc: the load resistance (RC) must be designed so that the closed contact current is under 100 mA.

Hi,
I'm having some issues connecting a pulse counter to my neuron: the pulse counter's led is flashing, indicating that it is sending out pulses, but the neuron isn't counting any pulses at all, and the green led to indicate action on I1.1 on the neuron is also not blinking, so I suspect that the pulse isn't seen by the neuron.
This is the diagram that was included with the pulse counter:

So I have connected 7 to DIGND and 6 to DI1.1, but nothing's happening. Did I make a mistake here?
The pulse duration is 90 ms, so I set the debounce of DI1.1 to 0. I also changed the scan_frequency parameter to 8 in /etc/evok.conf but this might be more important for the unipi?
What am I doing wrong?