Analog And Digital Monitor Output - Hitachi SJ100 Instruction Manual

Analog and Digital Monitor Output

In the system design for inverter applications it is useful to monitor the inverter operation
from a remote location. In some cases, this requires only a panel-mounted analog meter
(moving-coil type). In other cases, a controller device such as a PLC may command the
inverter frequency and other functions. Sometimes it is useful to have the inverter
transmit the (real-time) output frequency value back to the controller to confirm actual
operation. The monitor output function [FM] serves these purposes.
The inverter provides an analog/digital output
primarily for frequency monitoring on terminal
[FM] (frequency monitor). It uses terminal [L] as
analog GND reference. You can configure
terminal [FM] to transmit the inverter current
output or frequency output in pulse-width
modulated format (PWM). You can also config-
ure terminal [FM] to output the frequency value in a frequency-modulated (FM) format.
The following table lists terminal [FM] configurations. Use function C_23 to configure.
Func. Code
C_23
PWM Signal Type
The pulse-width modulated signal at terminal
[FM] is primarily designed for driving a moving-
coil meter. The PWM signal is automatically
averaged by the inertia of the moving-coil mecha-
nism—converting the PWM signal to an analog
representation. Be sure to use a 10V full-scale DC
voltmeter.
The signal characteristics of terminal [FM] in PWM configuration is shown below:
[FM]
10V
0V
To calibrate the meter reading, generate a full-scale output (always ON) at terminal
[FM]. Then use parameter B_81(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 B_81 so that the meter reads 60 Hz.
Description
00 Output frequency
01 Output current
02 Output frequency
Pulse-width modulation (analog)
t
T T = 4 ms
H O OI
A GND
Analog/digital Output
See I/O specs on page 4–6.
Waveform
PWM
PWM
FM
H O OI
[FM] Output
C_23 = 00 Inverter output frequency
Inverter output current
C_23 = 01
PWM scale factor
B 81
t
4–33
SJ100 Inverter
L FM CM2 12 11
Full Scale value
0 – Max. frequency (Hz)
0 – 200%
0 – Max. frequency (Hz)
L FM CM2 12 11
– +
0 to 10V,
1 mA
t
= -- -
T