Wiring up the Alarm output on Leadshine AM882

[irving2008]

Looking at the diagram in the manual again, I thought that if I use R = 4.7k, the PIC pin will see 5V when the FLT output is disabled, and 0V when the FLT output is enabled. With nothing passing through the FLT optotransistor in the EM806 ie. with no fault, the PIC pin should see 5VDC on the input, if the FLT optotransistor is enabled, it would pass current down to 0VDC, thus bringing the PIC pin down to 0VDC. Or am I missing something?

Regards,
T.

That was my option 2 and will work fine, but if you read page 3 of the manual you'll see it says that the output is low impedance in normal operation and goes high when there's a fault, i.e. the logic is reversed. The reason for this is if you put the pullup at the controller end and the cable gets broken or disconnected you get a fault condition.

@m_c you could use internal weak pull_up but needs to be turned on in s/w and is only 10k so more susceptible to noise in this environment. Indeed on reflection I'd probably use a 1k external pull_up for just that reason.