Terminal FM calibration (C0 (Pr.900))
• The output via terminal FM is set to the pulse output. By setting C0 (Pr.900), the meter connected to the inverter can be
calibrated by parameter setting without use of a calibration resistor.
• The pulse train output via terminal FM can be used for digital display on a digital counter. The output is 1440 pulses/s at
full scale. (Refer to
Pulse width T1: Adjust using calibration parameter C0
Pulse cycle T2: Set with Pr.55 (frequency monitor)
Not needed when the operation panel or the parameter unit is used for calibration.
Use a calibration resistor when the indicator (frequency meter) needs to be calibrated by a neighboring device because the indicator is located
far from the inverter.
However, the frequency meter needle may not deflect to full-scale if the calibration resistor is connected. In this case, perform calibration using
the operation panel or parameter unit.
In the initial setting, 1 mA full-scale and 1440 pulses/s terminal FM are used at 60 Hz.
• Calibrate the output via terminal FM in the following procedure.
Connect an indicator (frequency meter) across terminals FM and SD on the inverter. (Note the polarity. Terminal FM
When a calibration resistor has already been connected, adjust the resistance to "0" or remove the resistor.
Set a monitor item in Pr.54 AM terminal function selection. (Refer to
When the running frequency or inverter output current is selected on the monitor, set the running frequency or
current value at which the output signal will be 1440 pulses/s, using Pr.55 Frequency monitoring reference or
Pr.56 Current monitoring reference beforehand. Normally, at 1440 pulses/s the meter deflects to full-scale.
If the meter needle does not point to maximum even at maximum output, calibrate it with C0 (Pr.900).
• When outputting an item such as the output current, which cannot reach a 100% value easily by operation, set Pr.54 to "21"
(reference voltage output) and calibrate. A pulse train of 1440 pulses/s are output via terminal FM.
• When Pr.310 Analog meter voltage output selection = "21", the output via terminal AM cannot be calibrated. For the details
of Pr.310, refer to the Instruction Manual of the FR-A8AY.
• The wiring length to terminal FM should be 200 m at maximum.
• The initial value of the calibration parameter C0 (Pr.900) is set to 1 mA full-scale and 1440 pulses/s terminal FM pulse train
output at 60 Hz. The maximum pulse train output of terminal FM is 2400 pulses/s.
• When connecting a frequency meter between terminals FM-SD and monitoring the running frequency, it is necessary to
change Pr.55 to the maximum frequency, since the FM terminal output will be saturated at the initial value when the maximum
frequency reaches 100 Hz or greater.
• Calibration with the calibration parameter C0 (Pr.900) cannot be done when Pr.291 Pulse train I/O selection = "10, 11, 20,
21, or 100" (high-speed pulse train output).
Calibration procedure for terminal FM when using the operation panel
Turning ON the power of the inverter
The operation panel is in the monitor mode.
for the full-scale value of each monitor item.)
Set with Pr.56 (current monitor)
5.11 (M) Item and output signal for monitoring