Overview
- Analog outputs deliver continuous physical quantities, offering simplicity and quick response, ideal for small system feedback.
- Analog current outputs vary in range, necessitating compatibility checks for different devices.
- Issues like sensing errors and insufficient supply current can affect communication, requiring careful calibration and power management.
1. Analog Output
Analog output refers to a system's output of continuously varying physical quantities such as voltage and speed. Its advantages include intuitive operation, ease of use, and faster response times, making it suitable for small systems for information feedback. Analog outputs utilize specific electronic physical quantities, allowing for troubleshooting with a multimeter, offering simplicity and ease of understanding compared to other communication methods. The wiring requires one-to-one transmission, a dedicated line to a single terminal device, making it most suitable for feedback control due to its minimal delay. However, this one-to-one communication can be a disadvantage for larger systems due to the increased number of corresponding ports.
2. Analog current output
Analog current output utilizes current, measured in mA, with common ranges including 0-20mA, 4-20mA, and 0-24mA, among others. This variety can lead to compatibility issues, requiring verification of each machine's applicable range before use.
The 4-20mA signal is a standard for transmitting analog signals, where the output range of 4 to 20 milliamps (mA) corresponds to the measured physical values, like flow, pressure, and velocity. For example, in the context of instantaneous flow, 4mA might correspond to a flow rate of 40 liters per minute (Lpm), and 20mA to 200 Lpm, indicating a linear relationship between the signal and the physical quantity being measured.
As a standard communication method in the industrial sector, analog current output specifies only the physical quantity of the output, allowing for variations in aspects not specified, such as whether the main unit needs external power or if the 4-20mA output requires external power, or if the sensor outputs current directly, including variations in electrical connection.
3. Signal Reception Issues
1 ) Sensing Error
Discrepancies can occur when the output, such as 4.000, does not match the receiver's capability to discern, for example, between 4.0 and 4.1, leading to a mismatch in decimal places. Both the sending and receiving ends need to be accurate for the measurement to be meaningful. Various onsite conditions can cause deviations from expected results, necessitating the use of output fine-tuning features to adjust the output values precisely.
2 ) Solutions to Current Adjustment Issues
If the circuit's impedance is too high, preventing the expected adjustment of current, the issue can be addressed by either increasing the supply voltage or reducing the impedance.
3 ) Insufficient Supply Current Causing Unexpected Communication:
When many devices share a power source, insufficient supply current can lead to suboptimal communication and even sensor malfunctions.