The current voltage signal ring of transfer cart power supply system
2017-12-14
In ac circuit, current loop is an electrical signal transmission scheme which adopts current source and current receiver. For transfer cart the system adopts the current voltage signal, the voltage converter, and a remote current receiver that sends high-speed data at a large distance.A current loop may use different current level analog and digital communications.Analog current circuits usually correspond to a simulated value using a 4-20 milliampere signal level.
The signal scheme of transfer cart depends on the time required to increase and decrease the digital signal.An integrated circuit printed circuit board USES a voltage-driven scheme for a very short range of printed circuit boards.In the voltage driver circuit, the receiver detection voltage is very simple, because there is a minimum distribution inductance and capacitance, which may limit the transmission of the signal.
When a voltage driver of transfer cart is sent to a remote location, which is more than a few meters away, the signal takes time to reach the receiver and can't even reach the receiver in some cases.
Digital serial communication, current loop can use any current level in a safe range.At present, the digital signal of the level of electric car level, because of the nature of the wire circle "mark/space" or "1" and "0" - is usually the polarity reversal.In comparison, the serial bus can be driven using differential voltages, using a double strand to send one bit at a time, and send a bit, and the two lines will be used for a double-ended or balanced output.
In a similar application the current loop will send a signal voltage proportional to the current level and there is no direct voltage.Several factors that are to be dealt with in the voltage drive transmission terminal voltage.These include the output impedance of the drive circuit, the line of distributed capacitance and inductance, and the external electromagnetic noise.
In the current circuit, the current actuator can compensate the conductor's performance and external noise.Lugs transfer cart, for example, if a current loop transmitter to send 12 ma to the remote receiver shows that the simulation values, the same 12 ma even if the resistance of the conductor changed in the receiver is still available.This is due to the principle of controlled current source, which is intended to be 12 mah.If the loop characteristic changes fairly quickly, the generated current is still the same as the control current source.
