amp fault bit location

[bradp]

I’m not sure if my amplifier fault is set up correctly in the PPMAC. Initially the Amp Fault pointer was set to 0. Now I’ve set it to what I believe is the default (see below): [attachment=1390:name] Initially the “AmpFaultBit” was set to the default value of 23. With that setting the “AmpFault” was always on. So I monitored the “Acc24E2A[4].Chan[0].Status” value. This is what I noticed: [attachment=1391:name] Bit 23 was always on. So I guessed that bit 15 was the bit I should be using. It’s the only bit that changes state when not faulted or faulted. So now the “AmpFault” bit’s never coming on: [attachment=1392:name] I clearly missing something or I’m doing something wrong. Can you advise? Do I just need to do a reset after changing these values?

[bradp]

The PowerPmac is a 32-bit system. The Gate1 is a 24-bit system. In the world of "C" when the PowerPmac reads data from a Gate1 the data comes into the 24 MSBs of the PowerPmac's 32-bit word. You can see this as being a left shift of 8-bits. When you query Gate1[].Chan[].Status in an ASCII method you use command processor. The command processor knows this is only a 24-bit value and gets rid of the low 8-bits since they do not really exist. This is why you need to add 8-bits to what you see when looking directly at Gate1[].Chan[].Status through an ASCII interface. And this is why you must use Motor[].AmpFaultBit=23 for a Gate1.