Pwm (Fnc 58) - Mitsubishi FX1S Series Programming Manual

FX Series Programmable Controlers
5.6.9

PWM (FNC 58)

Mnemonic
PWM
FNC 58
( width
Pulse
modulation)
16 BIT OPERATION
Points to note:
a) Because this is a 16 bit instruction, the available time ranges for S
b) A calculation of the duty cycle is easily made by dividing S
value greater than S
between two pulses, i.e. a second pulse would start before the first had finished. If this is
programmed an error will occur.
This instruction is used where the length of the pulse is the primary concern.
c) The PWM instruction may only be used once in a users program.
d) Because of the nature of the high speed output, transistor output units should be used with
this instruction. Relay outputs will suffer from a greatly reduced life and will cause false
outputs to occur due to the mechanical 'bounce' of the contacts. To ensure a 'clean' output
signal when using transistor units, the load current should be 200mA or higher with the
FX2N Series. The load current should be 10 - 100mA with the FX1S/1N Series. It may be
found that 'pull up' resistors will be required.
Function
Generates a K, H,
pulse train with KnX, KnY, KnM,
defined pulse KnS,
characteristics T, C, D, V, Z
Note:
S1
S2
32 BIT OPERATION
as this would mean the pulse is on for longer than the distance
2
Operands
S S
1 2
Y
Note:
All units: Y000 or Y001
only
Operation:
A continuous pulse train is output through device D
when this instruction is driven. The characteristics
of the pulse are defined as:
The distance, in tim e (m sec), between two
identical parts of consecutive pulses (S
And how long, also in time (msec), a single pulse
will be active for (S
Applied Instructions 5
FX FX
1S 1N
Program steps
D
PWM:
7 steps
)
PULSE-P
).
1
and S are 1 to 32,767.
1 2
by S . Hence S
1 2
FX FX
2N 2NC
).
2
cannot have a
1
5-80