To check the RS485 signal with a True RMS Multimeter, follow these steps:
1. Confirm the wiring: Make sure the A and B terminals of the RS485 device are connected correctly. A is a non-inverting signal and B is an inverting signal.
2. Select the voltage measurement mode: Set the multimeter to DC voltage measurement mode, and the range should be set to at least 5V or higher to accommodate the RS485 signal voltage range (usually -7V to +12V).
3. Measure the signal line voltage:
- Connect the red probe of the multimeter to the A line and the black probe to the B line.
- During normal RS485 signal communication, the voltage difference between the A line and the B line should be between +1.5V and +5V (logical high level) or between -1.5V and -5V (logical low level).
4. Check signal fluctuations: During communication, the voltage between A and B should fluctuate with data transmission. If the voltage remains unchanged, it may indicate that the signal line is not transmitting data or the device is not working properly.
5. Troubleshooting:
- If the voltage is out of the normal range or has no fluctuations, check whether the line connection is loose, whether the terminal resistance is matched, or whether the device is working properly.
This method can determine whether the signal exists through the voltage difference of RS485, but it cannot measure the specific waveform of the signal. To obtain more detailed signal information, it is recommended to use an oscilloscope.
About Premier Cable
Premier Cable is a professional manufacturer of USB serial cables, serial converters, and cable assembly & wire harnesses, committed to providing customers with high-quality, stable, and reliable communication solutions. Our product line is complete, including USB to RS232, RS485, RS422, TTL, UART, and other interface conversion cables, as well as RS232 to RS485, RS422, TTL converters. For different application scenarios, we have launched innovative 2-in-1 and 4-in-1 functional design products to bring users a more efficient connection experience. Whether it is industrial automation, communication equipment, or test and measurement, Premier Cable can provide you with customized solutions.
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