Pb Pulse Input Signal fault in Toshiba drive
Pb Pulse Input Signal Error fault in Toshiba drive
Description Some applications use a Pulse Train (frequency pulses) as a speed reference instead of 4-20mA. This is common in simple follower applications or flow meters. "Pb" indicates a fault with this pulse input signal (usually on terminal RP or S4 depending on assignment). The drive is not receiving the pulses or the frequency is out of the measurable range. Causes
1. Frequency Mismatch: The PLC is sending 50kHz pulses, but the drive input is rated for max 30kHz.
2. Signal Level: The PLC is sending 5V pulses, but the drive expects 24V pulses (or vice versa), failing to trigger the optocoupler.
3. Wiring: Pulse inputs are highly sensitive to polarity. Reversing Positive and Negative will result in zero reading. Solution Check the specifications of the Pulse Input (RP). Verify the dip switches. Some terminals require a hardware switch to change from "Logic Input" to "Pulse Input."
Use an oscilloscope or a multimeter with a "Hz" (Hertz) function to measure the incoming signal. If you read 0Hz, the source is the problem. If you read a valid frequency (e.g., 1000Hz) but the drive shows "Pb," check the scaling parameters (Pulse Input Scaling) to ensure 1000Hz corresponds to a valid speed and not "0".
Description Some applications use a Pulse Train (frequency pulses) as a speed reference instead of 4-20mA. This is common in simple follower applications or flow meters. "Pb" indicates a fault with this pulse input signal (usually on terminal RP or S4 depending on assignment). The drive is not receiving the pulses or the frequency is out of the measurable range. Causes
1. Frequency Mismatch: The PLC is sending 50kHz pulses, but the drive input is rated for max 30kHz.
2. Signal Level: The PLC is sending 5V pulses, but the drive expects 24V pulses (or vice versa), failing to trigger the optocoupler.
3. Wiring: Pulse inputs are highly sensitive to polarity. Reversing Positive and Negative will result in zero reading. Solution Check the specifications of the Pulse Input (RP). Verify the dip switches. Some terminals require a hardware switch to change from "Logic Input" to "Pulse Input."
Use an oscilloscope or a multimeter with a "Hz" (Hertz) function to measure the incoming signal. If you read 0Hz, the source is the problem. If you read a valid frequency (e.g., 1000Hz) but the drive shows "Pb," check the scaling parameters (Pulse Input Scaling) to ensure 1000Hz corresponds to a valid speed and not "0".
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