GE Counters and Order of Operation MAIN 222 Industrial Controllers 9/19/2018

Introduction Program Execution See the sheet on Program Execution The PLC writes inputs to register then drives outputs Per each rung usually Sequence is very important 9/19/2018

Program Execution In class activity Order of Operations What is the difference between the programs? Which one is the one shot?   9/19/2018

Instruction Sets Output Type Instructions Right Side of the rungs Depend on logic Preceding it MOVE Instructions Time & Counters Internal Relays Math Instructions 9/19/2018

Positive Going Coil = 1 shot When we strobe an input such as a counter or timer we have problems with switch debounce. To prohibit this condition we need only one pulse per switch activation The 1 shot solves this problem by only allowing 1 shot regardless of the switch bouncing You can have a PGC as an output but micro90 does not like having multiple outputs with a PGC in it. 9/19/2018

Types Of Counters Up Counter Down Counter Counts Up (Increments Up) The output is on when when current value = or greater than preset value Down Counter Transition from off to on causing current value to decrease by 1 Output is on when current value is less than or equal to preset value 9/19/2018

Differences between PLCs GE PLCS Counters and Timers are functions that give an output AB PLCS Counter and timers are functions that give an output MITSUBISHI PLCS Like Koyo and TI the counter and timer are outputs, that is they are not a function they are an output The address of output is used to drive or do something 9/19/2018

Counter Set up To address a counter or any other type of internal function use %R Every counter or timer address must be incremented by 3 words %R1 %R4 %R7 The counter uses 3 Register #s to store the data If we don’t, registry is over lapped Trying to save the data for 2 counters in one location 9/19/2018

Addressing A Counter The Input This is the location where the change of state is observed (can be from an actual input, other function ie counter or and output) The Reset An address that confirms resetting the PV (preset value) back to its original value. Note that we can “lock” the counter out if the reset input is forced ON If we need to create a reset that resets the Counter we can in the Reset line (parallel with actual reset command such as %I2) use a FST_SCN a first scan command that will reset all values when the PLC is first scanned in the run mode The PV The Preset value is the address numerically after the counter number If we have %R2 as a counter then %R3 is the PV registry Highest Number is 32767 We can have a Hardcode value a set value such as 10, 10000 ect. Or we can have %R, %AQ or a %AI variable as its PV 9/19/2018

Universal Counter Info All PLCs use 3 words for addressing the counter GE uses a %R register because it gives greatest flexibility For example Mitsubishi has C=256, T=256 and D=1028 so what if you need 270 counters cannot do it! GE has in the Micro 90 2056 %R so that gives us 685 (2056/3) anything Timer or Counters 9/19/2018

Special Note Resetting R value We have to have an ALWAYS_ON in series with the INPUT rung to COUNTERS and TIMERS on the Series 90 Micros. It is caused by a function of the programming of the VersaPro software. In the Mitsubishi PLC the command is 9038 9/19/2018

Where to Get More Information See Web Site VersaPro 2.02/3 users guide Series 90 Micro Workshop Believe it or not the help in VersaPro Then Index Look up counters 9/19/2018