Encoder

[Charles_DeJesus]

Hi,

 

I have built a fixture to read stop time of a saw blade after turn switch tool OFF. For hardware I’m using the following : NI-PCI 6602 Card, SCB-60 Connector block, SSR Backplane (for digital signal), current operated switch, and Encoder model TRD-S1000-VD (1000 counts/Rev). And for software I’m using LabVIEW 8.5.1. I have attach the encoder to the blade saw  to monitor blade when stop costing and utilize the current sensor to monitor no current  and send the signal to a digital input to trigger costing time. I create a software program with this sequence:

 

Step 1) Turn  ON tool switch for 6 seconds (so tool can reach full RPMs, about 4000).

Step 2) Turn OFF tool switch and monitor current with current sensor (no current in the circuit will trigger the encoder. Monitor current is done in case if tool switch stucks.

Step 3) If no current in the circuit, start timer (to time blade costing) and start monitoring saw blade RPMs with the encoder counts.

Step 4) Stop timer when blade RPMs drops below 30 rpms. (30 rpms it considers stop time) and record how long the blade took to come to stop time.

Step 5) Wait for 16 seconds and go to step 1 (start cycles again)

 

In the software program, I record number of cycles and time of each cycle, which is the costing time of the blade after sensing no current. The problem I have is zero time recorded on some cycles. I have recorded 1000 cycles on chart graph and 10 cycles out of a 1000 had zero data as time, blade costing time, even though the blade was spinning. I think that my program application records missing randomly because sometime there is more than 10 cycles and sometimes is less than 10 cycles missing  in a 1000 cycles. I want to fix glitch to avoid this zero data record.

 

Attach is 3 pictures two of them are graphs with cycles vs. stop time. One graph has 1000 cycles recorded and you can see the zero time recorded in a cycle. The other graph has 37500 cycles recorded and you can see that there are a lot missings and this is not acceptable. The third picture is the block diagram of the VI I’m using to monitor encoder pulses, no current, and stop time of the blade.

 

Any help would be greatly appreciated.

 

Thanks,

Carlo.s