Why is it forbidden to use a passive 485 converter

How do you tell "Passive 485 converters are forbidden"?

Passive 485 converters usually require a standard DB9 RS232 serial port, so that they can steal power from the standard RS232 serial port!

If you can't steal power, the 485 converter won't work properly.

Please see Wuhan Hongwei Optoelectronics.

E485C RS-232 RS-485 422 Passive Converter.

Peculiarity. RS-232 RS-485 422 conversion, RS422 four-wire full-duplex, RS485 two-wire half-duplex communication.

Up to 95% efficiency serial power theft technology, no external power supply is required.

It is equipped with an integrated industrial terminal block and a standard DB9 hole serial port.

Unique serial port protection circuit, which can be hot-swapped with electricity.

The built-in intelligent module automatically identifies the flow direction of RS-485 signals, eliminating the need for CTS flow control.

Built-in 600W ms anti-lightning protection and 15kV anti-static protection.

Transparent transmission, baud rate adaptation, no need to change user protocol.

The passive 485 converter has no external power supply, and the standard 9-wire RS232 stealing technology is used, and your device must be using a 3-wire serial port, and the 485 converter can only be used for this kind of serial port.

Passive ones can be used, just use them! Active can't be used, is it done on your circuit board?

The passive converter automatically switches the transmitting and receiving states.

Your active one probably can't automatically switch between sending and receiving.

With an alternative method, replace it with a module that can communicate.

Maybe it's the problem with the active converter you're using.

485 converter, because most computers do not have RS-485 interface, RS-485 serial port must be converted to RS-232 serial port through 485 converter to communicate with the computer, 485 converter is divided into passive type, active lightning protection type, active lightning protection optical isolation type, passive type 485 converter is supplied by stealing electricity from the RS-232 serial port of the computer, because it is through the serial port stealing electricity, the power can not be too high and its size is small, Cause its corresponding protective devices can not be used too much, passive 485 converter is generally used for less load, short communication distance of the 485 bus network, active lightning protection type 485 converter is external power supply, in the 485 port with lightning protection function, can be in the case of external lightning strike on the 485 line discharge effect, so as to protect the 485 port chip from damage, but if the lightning exceeds a certain limit, it will still lead to 485 port chip damage and even lead to computer damage. Active lightning protection optical isolation type 485 converter is to add 485 signal isolation and power isolation two protection functions on the active lightning protection type, 485 signal isolation using optocoupler isolation, electrical signal through optocoupler into optical signal, and then through optocoupler to convert optical signal into electrical signal, optocoupler is similar to the role of fuse, when there is a strong current coming, may cause the optocoupler to burn out, but it will never affect the other end, power isolation is the use of dc dc isolation, the principle is similar to a fuse, The strong voltage and strong current will cause the DC DC isolator to burn up at most, and will not affect the other end, thus ensuring that the computer serial port will not be burned.

The active nature of the converter means that the converter needs an external power supply to work properly!

Passive means that there is no need for an external power supply.

It also works, but it is true that this converter is stealing electricity from the input such as the RS232 interface!

Therefore, there are usually requirements for RS232 serial interface, such as the standard RS232 interface of the computer.

Such as Wuhan Hongwei Optoelectronics.

E485C RS-232 RS-485 422 Passive ConverterE485D RS-232 RS-485 422 Active Isolated Converter.

Why not choose a terminal block?

Please see Hongwei Optoelectronics.

485A 232 485 Passive Converter.

485B 232 485 Active Isolation Converter.

The 485c 232 485 422 passive converter is all supplied with terminal blocks with detailed instructions!

The terminal block is much easier than connecting a pin or hole in the DB9!

Good luck.

I've used two passive 485 232 pairings, and the quality of the converter itself has something to do with it, change it, when it's unsuccessful, it's mostly recommended, or use active.

RS232 to RS485 Converter:

active, that is, connected to an external transformer.

Passive, there is no external transformer, but it will steal electricity from the serial port, and the stability of the active power supply for the converter is better than that of the passive, after all, stealing electricity is disgraceful, hehe.

1 Different transfer modes.

The RS 232 uses an unbalanced transmission mode, i.e. single-ended communication.

Whereas, RS485 uses balanced transmission, i.e., differential transmission. The RS 232 uses an unbalanced transmission mode, i.e. single-ended communication. The data signal at the receiving and sending ends is relative to the signal ground, e.g. when using a DB25 connector, the data sent from the DTE device is 2 feet relative to 7 feet (signal ground) level.

2 Different transmission distances.

RS 232 is suitable for communication between local devices, and the transmission distance is generally not more than 20m.

RS 485 has a transmission distance of tens to several kilometers.

3 different transfer units.

RS 232 only allows one-to-one communication.

The RS 485 interface on the bus allows up to 128 transceivers to be connected. A typical RS 232 signal oscillates between positive and negative levels. When sending data, the transmitter drives the output with a positive level of 5 15V and a negative level of 5 15V.

Passive is serial port power theft, no need for external power supply.

An external power supply is required for active use.

Please see Wuhan Hongwei Optoelectronics.

E485A RS232 RS485 Passive Converter E485B RS232 RS485 Active Isolation Converter E485C RS232 RS485 RS422 Passive Converter E485D RS232 RS485 RS422 Active Isolation Converter.

It is to convert the RS232 signal of the serial port of the computer into a 485 signal that can be connected to the 485 device.

The power supply required for the circuit is obtained by the serial port of the computer, and it is not connected to an external power supply, such as Wuhan Hongwei Optoelectronics.

E485A RS232 RS485 Passive Converter E485C RS232 RS485 RS422 Passive Converter.

Is the rs232 485 converter passive or active?

E485C RS232 to RS422 RS485 Interface Converter Features RS485 two-wire half-duplex communication, RS422 four-wire full-duplex unique serial port protection circuit, can be hot-swapped.

Built-in intelligent module, automatically identify RS485 signal flow direction, no need for CTS flow control Signal line 600W ms lightning protection and 15kV antistatic protection Transparent transmission, baud rate adaptation, no need to change user protocol The maximum number of nodes is 128

How are you doing?

Could it be a lack of power?

485 converter, since most computers do not have an RS-485 interface, the RS-485 serial port must be converted to RS-232 serial port through the 485 converter to communicate with the computer.

The 485 converter is divided into passive type, active lightning protection type, and active lightning protection optical isolation type.

1] Passive 485 converter is supplied by stealing electricity from the RS-232 serial port of the computer, because it is through the serial port, the power can not be too high and its size is small, resulting in its corresponding protection devices can not be used too much, and the passive 485 converter is generally used for the 485 bus network with less load and short communication distance.

2] The active lightning protection 485 converter is powered by an external power supply, with lightning protection function in the 485 port, which can discharge the 485 line in the case of an external lightning strike, so as to protect the 485 port chip from being damaged, but if the lightning strike exceeds a certain limit, it will still cause the 485 port chip to be damaged or even lead to computer damage.

3] Active lightning protection optical isolation type 485 converter is to add 485 signal isolation and power isolation two protection functions on the active lightning protection type, 485 signal isolation using optocoupler isolation, electrical signal through optocoupler into optical signal, and then through optocoupler optical signal into electrical signal, optocoupler is similar to the role of fuse, when there is a strong current coming, may cause the optocoupler to burn out, but will never affect the other end, power isolation is the use of dc dc isolation, the principle is similar to the fuse, The strong voltage and strong current will cause the DC DC isolator to burn up at most, and will not affect the other end, thus ensuring that the computer serial port will not be burned.

Isolation means that when the two systems are connected through the circuit, they do not interfere with each other and do not communicate with each other to prevent mutual interference and damage. When not isolated, there is an electrical connection between the two systems. It is easy to interfere with each other and damage.

Active isolation, i.e. connecting an external transformer.

Passive isolation, there is no external transformer, but it will steal power from the serial port to power the converter. Active stability is better than passive.

RS485 converter, since most computers do not have RS-485 interface, you must convert RS-485 serial port to RS-232 serial port through 485 converter to communicate with the computer.

RS485 converters are divided into passive type, active lightning protection type, and active lightning protection optical isolation type.

Friends upstairs Answer Well done! Usually isolation is the use of optoelectronic isolation components in the circuit! 485ARS-232 RS-485 Passive Converter 2-wire half-duplex, serial port power theft, no external power supply required0 Remote multi-machine 128-node 485B RS-232 RS-485 Active Isolation Converter 2-wire half-duplex, isolated conversion, external +5V power supply rate0 Remote multi-machine 128-node 485C RS-232 RS-485 422 passive converter Full-duplex, half-duplex universal, no external power supply required; Rate0 Remote Multi-machine 128 Node 485D RS-232 RS-485 422 Active Isolation Converter Full-duplex, half-duplex general-purpose, isolated conversion, external +5V power supply rate 0 Remote multi-machine 128 nodes.