Internet PLC Forum

I seem to have overload my FMD with too much to do and not enough time to get it done, so I am going to pair it with a Nano which will handle to most time sensitive routine with little to output.  However, the Nano will generate some numbers that the FMD will need.  So is it better for the Nano to write to the FMD or is it better to have the FMD read the Nano? (via MODBUS)  Using the Nano to write, I can control when it does so,  not true with a read by the FMD.  Does the 'writing' get done before the ladder cycle completes or after all the outputs have been set?

On a related subject; I am reading 64 variables from the FMD every 300 ms (via Host Link Protocol).  Is this affecting the ladder logic execution or are the communication functions separate from the main processor?  

I know I'm splitting hairs, but I'm getting some really strange results that can't all be blamed on 'noise'.  Thank you for any guidance anyone can provide.

I have an FMD16-16 that is giving me fits.
Basically the plc has to monitor a shaft that is turning up to 90 RPMs and do some different things depending on other inputs.  I have an arm that passes a proximity sensor every revolution and I use the pulse period to calculate the speed of the shaft every scan.  While the shaft is making one revolution, another sensor is picking up 1 to 9 pulses very quickly. I think I have attached the program which has 31 rungs of ladder logic (not counting comments) and there are 22 custom functions which contain 55 IF/Then statements, some of which are nested.  I also read all 8 analog inputs, some 3 times quickly, as well as do several For I=1 to 10 Loops and control two PWM outputs.  Along with all that, I am asking for 64 bytes of data via a router and the hostlink protocol every 1/4 second.  I'm wondering if my problem stems from asking the processor to do all of it's work in the 2/3 of a second that it takes the shaft to turn one revolution.  What happens is that my RPM reading randomly goes way out of range and when I try to record it in memory, I sometimes get a double entry.
The problem started when I added this code: (and the function 'EndTrip' is called)
   IF juice_switch=1
      IF TESTIO(pickup) SETIO PumpOut SETPWM 2,5000,5 REM nozzle rate?
         IF injector_pump=1 SETPWM 1,7000,10 REM injector rate?
         ELSE SETPWM 1,3000,10  SETIO nozzles2 REM nozzles2 rate?
         ENDIF
      ENDIF
   ELSE CALL JuiceOff REM everthing off!
   ENDIF REM no juice

juice_switch is a DM memory location that I can toggle between 0 and 1.  pickup is input7.  Everything works fine up the point that I turn 'pickup' on WHETHER juice_switch IS ZERO OR ONE!??  Tried rewiring to input8 with the same results.  In my mind 'pickup' should not even come into play if 'juice_switch' = 0.

 I don't have a good concept of how fast a processor can do its calculations?  Is there a chance that I can't have the plc do everything I want in 2/3 of a second?  Is the PULSEPERIOD command interrupting the ladder logic?  It does recover and keep running, but the out of range RPM reading causes other problems.   How can I test this? What else could be wrong?

Is it just me or others having this problem:  In the past I have run several nano's and monitored them with my laptop running trilogi 6.??.  This year I had to goto FMD16-16's and upgraded to trilogi 6.45.  I'm using basically the same program as on the nano's and everything works as expected in simulation mode.  However, when I try to monitor/control the plc from my laptop, clicking on the inputs makes them act like one-shot inputs (they are not).  I see the input led light briefly, but that's it.  In the past, and in simulation mode, a left click acts like a momentary contact (on when held on and off when released), and a right click latches the input on.  Also the inputs work correctly via switches or sensors.  The problem seems to be in the monitoring program...

I thought I'd be a good boy and upgrade to JRE 1.4.2_19 and v6.45 from 6.41 and have done so.  Now I can't navigate to load my old files!!  I did copy an old file to C:\TRiLOGI\TL6\usr and was able to open it, but am still unable to saveas to anywhere except the usr folder.  I know that I'm dumber than a stone, but I thought I had mastered the widows file system.  WTF am I missing??