Sotu And Sotd (Single Output Up And Down) - IDEC MICROSmart FC6A Series Ladder Programming Manual

4: B I
ASIC NSTRUCTIONS

SOTU and SOTD (Single Output Up and Down)

The SOTU instruction "looks for" the transition of a given input from off to on. The SOTD instruction looks for the transition of a
given input from on to off. When this transition occurs, the desired output will turn on for the length of one scan. The SOTU or
SOTD instruction converts an input signal to a "one-shot" pulse signal.
A total of 3,072 SOTU and SOTD instructions can be used in a user program.
If operation is started while the given input is already on, the SOTU output will not turn on. The transition from off to on is what
triggers the SOTU instruction.
The SOTU or SOTD instructions 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.
When a CPU relay is defined as the SOTU or SOTD output, it may not operate if the scan time is not compatible with relay
requirements.
Ladder Diagram
SOTU
I0 Q0
SOTD
I0 Q1
Note: For restrictions on ladder programming of SOTU and SOTD instructions, see "Restriction on Ladder Programming" on page 4-33.
Timing Chart
ON
Input I0
OFF
ON
Output Q0
OFF
ON
Output Q1
OFF
Note: "T" equals one scan time (one-shot pulse).
There is a special case when the SOTU and SOTD instructions are used between the MCS and MCR instructions (see "MCS and
MCR (Master Control Set and Reset)" on page 4-29). If input I2 to the SOTU instruction turns on while input I1 to the MCS
instruction is on, then the SOTU output turns on. If input I2 to the SOTD instruction turns off while input I1 is on, then the SOTD
output turns on. If input I1 turns on while input I2 is on, then the SOTU output turns on. However, if input I1 turns off while input
I2 is on, then the SOTD output does not turn on as shown below.
Ladder Diagram
MCS
I1
SOTU
I2 M1
SOTD
I2 M2
MCR
4-28
Program List
Instruction Data
LOD I0
SOTU
OUT Q0
LOD I0
SOTD
OUT Q1
T
T T
Timing Chart
Input I1
Input I2
SOTU Output M1
SOTD Output M2
FC6A S MICROS
ERIES MART
T
ON
OFF
ON
OFF
ON
OFF
ON
OFF
L P M
ADDER ROGRAMMING ANUAL
No Output No Output
FC9Y-B1726