grover1
Member
I have a lightly populated SLC 5/03 (1747-L531) single rack with a 1746-FIO4V fast analog installed. The machine is measuring the voltage output of a strain gauge amplifier. We are interested in increasing machine speed by 25%, which drops the cycle time from 52msec down to 38msec. Scan rate variation of course becomes more pronounced as cycle time decreases. S:23 is 4msec with an occasional S:22 12msec that won't clear, which confirms variations I see in data returned by the process.
The ladder currently uses an IIM instruction on an unconditional rung to initiate the subroutine which stores and processes the analog input.
My question: Will an STI instruction, when set to interrupt once every 1msec, offer any significant improvement? I just want to measure at the exact same point within the cycle, every cycle (well, closer than we do now). If so, will the presence of the STI instruction adversely affect the existing scan rate?
I searched some of the IIM and STI threads, but was unable to draw a conclusion for this application. Any help is greatly appreciated.
Grover
The ladder currently uses an IIM instruction on an unconditional rung to initiate the subroutine which stores and processes the analog input.
My question: Will an STI instruction, when set to interrupt once every 1msec, offer any significant improvement? I just want to measure at the exact same point within the cycle, every cycle (well, closer than we do now). If so, will the presence of the STI instruction adversely affect the existing scan rate?
I searched some of the IIM and STI threads, but was unable to draw a conclusion for this application. Any help is greatly appreciated.
Grover