4–63

SJ300 Inverter

To calibrate the meter reading, generate a full-scale output (always ON) at terminal [FM]. Then use parameter B081(gain setting from 0 to 255) to adjust the corresponding full-scale reading of the meter. For example, when the inverter output frequency is 60 Hz, change the value of B081 so that the meter reads 60 Hz.

TIP: When using the analog meter for monitoring, adjust the meter so it has a zero reading when the [FM] output is zero. Then use scale factor B081 to adjust the [FM] output so the maximum frequency in the inverter corresponds to a full-scale reading on the meter.

NOTE: The indicator accuracy after adjustment is about ±5%. Depending on the motor, the accuracy may exceed this value.

PWM Smoothing Circuit – Note that standard analog output signals are available on terminals [AM] and [AMI], covered in the next section. However, you may also wish to smooth the PWM signal at the [FM] terminal and convert it to an analog signal. The [FM] terminal will then generate a relatively stable DC analog voltage that represents the output value. To do this, use the circuit shown to the right. Note the output impedance of the circuit is at least 82kΩ, so the monitoring device needs an input impedance of 1MΩ or greater. Otherwise, the impedance of the smoothing circuit will cause a nonlinearity in the reading.

H O2 AM FM TH FW

L O OI AMI P24PLCCM1

82kΩ

+ +

Ω

μ

 

+

 

Volts

 

 

33k

1 F

 

 

 

 

–

 

 

 

 

 

–

 

 

 

 

 

 

 

 

 

 

 

Operations and

FM Signal Type The frequency-modulatedoutput at terminal [FM] varies its frequency with the inverter output frequency (when C027=03). The signal at [FM] uses the parameter A004 Maximum frequency setting. For example, if A004 = 60 Hz, then the maximum signal value at [FM] will be at

60 Hz. This frequency is digitally controlled for accuracy, and does not use the B081 gain setting when C027=03 (frequency modulation).

50% fixed duty cycle [FM]

 

 

 

 

 

 

 

 

 

 

 

 

 

 

---[FM] Output Frequency = T

10V

 

 

 

 

 

 

 

 

 

1

0V

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Selects FM type output

 

 

 

 

 

 

 

 

 

 

 

 

 

C027=03

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

T

 

 

 

 

 

 

t

 

 

 

 

 

 

 

 

 

 

1

 

 

 

 

 

 

 

 

T =

 

 

 

 

 

 

 

 

[FM]---------------------------------------------------------Output Frequency

Monitoring