1769-hsc question

I converted a program from ML1500 to 1769-l36 compactlogix adding a 1769-HSC. there is no 100 us option for the input filter in the HSC configuration tab, just 10 us, 500 us and 5 ms. Would the result be the same if I use 10 us and divide the raw(ctr0CurrentCount) by 10? The scaler in the 1769-hsc config is set to 1. the encoder resolution is 360 so I set the min and max count to 0 and 359 respectively, used ring counter(for angle measurement),encoder X1. update time 10ms. RPI is 10ms.

I also programmed 2 options to find the angle: either to use the raw value as the angle or compute the change as rdcast used here http://www.plctalk.net/qanda/showthread.php?t=49549:
SUB HSC_RAW_COUNTER_IN Last_Scan_Value Scan_Delta_Count MOV HSC_RAW_COUNTER_IN Last_Scan_Value ADD Scan_Delta_Count Total_Counts Total_Counts

Another question is I read that Local:1:I.Ctr0Overflow is set when a pulse is received after 359 so I should just reset Local:1:O.Ctr1ResetCountOverflow when Local:1:I.Ctr0Overflow is present? The Z signal was not used in the ML program.

Why would you divide the input count because you changed the filter?

And if you are maintaining your own count off of the delta, you don't have to worry about resetting anything on the HSC module. The simplicity of just using the HSC count, and ignoring it's multiple configuration options as well as the ease of remembering the count through power downs are why I use the Delta method.

the change in input filter will result in change in input count, since 10 us > 100 us, there will be more count than the usual AFAIK.

I would still like to use the raw and not the count off the delta since this is the exact angle already and the manual says that if the count goes over the max count(meaning encoder sends another pulse?) it will set the overflow bit and stop the count so i need to reset, or that will not happen? the z is not configured yet so this HSC will only count up.

No, the filter is just there to filter out noisy signals. It doesn't magically change the number of counts being received (unless you are setting it to say 5mS and looking for a 250kHz input signal.

And for just using the module counting, I thought that module could function as a direct ring counter. Just set the CtrMinCount and CtrMaxCount settings.

Thanks rdcast, I guess I will confirm that filter on site. maybe 10us is ok as filter.

yeah 0-359 is already set.Im just concerned with the overflow bit stopping the count. Im not able to test if the ring counter will not overflow and just merrily go back to 0 after 359.

when is it safe to preset the currentcount aside from when the encoder is stopped and disabled?

I might have to use your method of getting the delta for the angle, but I have a problem since the currentcount cannot be reset immediately(unlike in ml1500) during running state(continuous cycle) since it will set the presetwarning bit correct? but if i set maxcount to 2 billion, i think the machine has to stop before it reaches that count.

Honestly, I can't help you with that... I literally haven't bothered with any of the control aspects of a counter module in more than 10 years.

I just let it count, mask off an appropriate number of bits, and handle my counters internally off of the scan to scan change.

I suppose, technically, I would have a problem if a counter rolled over at an odd value, but so far I've never seen anything but a normal binary progression in at least the lower 8 bits.