IDEC MICROSmart FC6A Series Ladder Programming Manual page 105

Timer Circuit
The preset value 0 through 65,535 can be designated using a data register; then the data of the data register becomes the preset
value. Directly after the TML, TIM, TMH, or TMS instruction, the OUT, OUTN, SET, RST, TML, TIM, TMH, TMS, TMLO, TIMO, TMHO,
or TMSO instruction can be programmed.
Ladder Diagram
TIM T5
D10
I1
• Countdown from the preset value is initiated when the operation result directly before the timer input is on.
• The timer output turns on when the current value (timed value) reaches 0.
• The current value returns to the preset value when the timer input is off.
• Timer preset and current values can be changed using WindLDR without downloading the entire program to the CPU again. From the
WindLDR menu bar, select Online > Monitor > Monitor, then Online > Custom > New Custom Monitor.
• If a timer preset value is changed during countdown, the timer remains unchanged for that cycle. The change will be reflected in the next
time cycle.
• If a timer preset value is changed to 0, then the timer stops operation, and the timer output is turned on immediately.
• If a current value is changed during countdown, the change becomes effective immediately.
• For data movement when changing, confirming, and clearing preset values, see "Changing, Confirming, and Clearing Preset Values for Timers
and Counters" on page 4-19. Preset values can also be changed and confirmed using the LCD screen and pushbuttons.
• WindLDR ladder diagrams show TP (timer preset value) and TC (timer current value) in advanced instruction devices.
• The timer instructions (TML, TIM, TMH, TMS) and off-delay timer instructions (TMLO, TIMO, TMHO, TMSO) cannot be used in an interrupt
program.
• If used, a user program execution error will result, turning on special internal relay M8004 and the ERR LED on the FC6A Series MICROSmart.
For details about the user program execution errors, see "User Program Execution Errors" on page 3-10.
Timer Accuracy
Timer accuracy due to software configuration depends on three factors: timer input error, timer counting error, and timeout output
error. These errors are not constant but vary with the user program and other causes.
Timer Input Error
The input status is read at the END processing and stored to the input RAM. So, an error occurs depending on the timing when the
timer input turns on in a scan cycle. The same error occurs on normal input and catch input. The timer input error shown below
does not include input delay caused by the hardware.
Program Processing
ON
Actual Input
OFF
ON
Input RAM
OFF
Timer Start
When the input turns on immediately before END processing,
Tie is almost 0. Then the timer input error is only Tet (behind
error) and is at its minimum.
Tie: Time from input turning on to END processing
Tet: Time from END processing to the timer instruction execution
Program List
Instruction
LOD
Q0
TIM
OUT
Minimum Error
END TIM END
Tie
Tet
1 scan time
FC6A S MICROS
ERIES
Data
I1
T5
D10
Q0
Program Processing
Actual Input
Input RAM
Timer Start
When the input turns on immediately after END processing, Tie is
almost equal to one scan time. Then the timer input error is Tie +
Tet = one scan time + Tet (behind error) and is at its maximum.
L P
MART ADDER ROGRAMMING
4: B
Note: For restrictions on ladder programming of
timer instructions, see "Restriction on Ladder
Programming" on page 4-33.
Maximum Error
END TIM
ON
OFF
ON
OFF
Tie
1 scan time
M FC9Y-B1726
ANUAL
I
ASIC NSTRUCTIONS
END TIM
Tet
4-9