CN208316749U - A kind of RS485 bus communication circuit based on transformer - Google Patents
A kind of RS485 bus communication circuit based on transformer Download PDFInfo
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- CN208316749U CN208316749U CN201821003984.9U CN201821003984U CN208316749U CN 208316749 U CN208316749 U CN 208316749U CN 201821003984 U CN201821003984 U CN 201821003984U CN 208316749 U CN208316749 U CN 208316749U
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Abstract
The utility model relates to a kind of RS485 bus communication circuit based on transformer, the circuit is with CN1, CN2 is network interface connector, RS485 signal passes through the 3rd foot of network interface, 6 feet, signal in bus is connected to primary terminal the 1st through cable, 2 feet, signal is transferred to secondary side through transformer, the 3rd foot of transformer is connected to the 1st foot of common mode inductance and the 2nd foot of D1, the 4th foot of transformer is connected to the 2nd foot of common mode inductance and the 1st foot of D1, the 3rd foot of D1 is connected to GND, Circuit Fault on Secondary Transformer, which is powered on GND, holds C1 and C2, signal reaches U1 the 7th after common mode inductance filters, 8 feet, the 8th foot of U1 is connected to Vcc, and C3 is held in power-up over the ground, U1 the 2nd, 5 feet are connected to GND, U1 the 1st, 3, 4 feet are connected to MCU.Take the utility model, improve anti-interference ability, preferably solve the technical problem of bus type RS485 isolator design complexity, have the characteristics that it is compatible, simple and practical, should be readily appreciated that and control, long service life and design cost is low.
Description
Technical field
The utility model relates to a kind of RS485 bus communication circuit based on transformer.
Background technique
RS485 is a kind of serial communication interface of low rate, is widely applied extensively and industrial circle, supports point-to-points thirty
Duplex data communication, receiving and transmitting signal timesharing occupy same bus (twisted pair).To avoid bus collision, A, B line are by core when 0 level
Piece output end really drives, and makes the V of UB-UA=5;And when 1 level or high resistant, A, B line is presented in bus empty used time, chip output
Change and biased by outer connecting resistance, and makes UA slightly larger than UB.Usually there is biggish earth potential difference in teledata connection, be consequently formed
It often will cause error code or hardware damage when common mode interference is excessive or under strong interference environment.Currently, in order to improve anti-interference ability,
Isolation RS 485 scheme is generallyd use, there is following two mode, first is that being individually insulated T (transmission) signal using optocoupler, R (connects
Receive) signal, RE, DE(selection), this mode is circuit complexity, and compares other isolation schemes, light-coupled isolation scheme power consumption
The cost of maximum, photo-coupler technology can be increased substantially as data rate improves, and manufacture complexity also can be with device
Quantity increases and improves, and optocoupler can have the life problems of ageing failure, and circuit diagram is referring to Fig. 1;Second is that directlying adopt
RS485 isolating chip, but because integrated chip solution alternative is not high at this stage, cause purchase cost higher, and each family
Integrated chip can not be compatible with, and later product batch may have that the friendship phase is longer and expects without substitution, cause product flexible
Property it is insufficient, circuit diagram is referring to fig. 2.
Summary of the invention
The purpose of this utility model is to be provided one kind using pulse transformer isolation method for above-mentioned deficiency and be based on
The RS485 bus communication circuit of transformer.
The technical solution adopted by the present invention is that: a kind of RS485 bus communication circuit based on transformer, it is characterised in that with
CN1, CN2 are standard network interface connector, and RS485 signal A, B pass through the 3rd foot of network interface and the 6th foot, the signal warp on two-wire bus
Cross that cable is connected to the 1st foot of pulse transformer primary terminal and the 2nd foot, signal are transferred to secondary side after pulse transformer,
The 3rd foot of pulse transformer is connected to the 1st foot of common mode inductance and the 2nd foot of D1, and the 4th foot of pulse transformer is connected to common mode electricity
2nd foot of sense and the 1st foot of D1, the 3rd foot of D1 are connected to GND, and pulse transformer secondary side, which is powered on GND, holds C1 and C2, letter
The 7th foot and the 8th foot of U1 are reached number after common mode inductance filters, the 8th foot of U1 is connected to Vcc, and C3 is held in power-up over the ground, U1's
2nd foot and the 5th foot are connected to GND, and the 1st foot, the 3rd foot and the 4th foot of U1 is connected to MCU, finally realize RS485 communication every
From;Wherein pulse transformer is isolated for node;TVS pipe back clamping is in 5V, for protecting the RS485 inside bus to communicate core
Piece, forward direction by voltage clamp in 0.7 V, when for maintaining high level and when bus free in bus between other RS485 chip A, B
Required newest bias voltage, and make other absorption pulse transformer rings.
The utility model is taken, is isolated using pulse transformer, anti-interference ability is not only increased, preferably solution bus
The technical problem of formula RS485 isolator design complexity, and without be provided separately isolated power supply can signal isolation, without consider
Data flow, and baud rate is adaptive in limited range, have the characteristics that it is compatible, simple and practical, should be readily appreciated that and control, together
When transformer the service life is longer compared to other products, and design cost is low.
Detailed description of the invention
Fig. 1 is a kind of one of the circuit diagram of isolation RS 485 scheme in the prior art.
Fig. 2 is the two of the circuit diagram of a kind of isolation RS 485 scheme in the prior art.
Fig. 3 is the circuit diagram of the utility model.
Specific embodiment
Below with reference to specific embodiment, the utility model is described in further detail.
Referring to Fig.1, in the RS485 bus communication circuit at this based on transformer, using CN1, CN2 as standard network interface connection
Device, RS485 signal A, B pass through the 3rd foot of network interface and the 6th foot, and the signal on two-wire bus is connected to pulse transforming by cable
The 1st foot of device primary terminals and the 2nd foot, signal are transferred to secondary side after pulse transformer, and the 3rd foot of pulse transformer is connected to
4th foot of the 1st foot of common mode inductance and the 2nd foot of D1, pulse transformer is connected to the 2nd foot of common mode inductance and the 1st foot of D1,
The 3rd foot of D1 is connected to GND, and pulse transformer secondary side, which is powered on GND, holds C1 and C2, and signal arrives after common mode inductance filters
Up to the 7th foot of U1 and the 8th foot, the 8th foot of U1 is connected to Vcc, and C3 is held in power-up over the ground, and the 2nd foot of U1 and the 5th foot are connected to GND,
The 1st foot, the 3rd foot and the 4th foot of U1 is connected to MCU, finally realizes the isolation of RS485 communication;Wherein pulse transformer is for saving
Point isolation;TVS pipe back clamping is in 5V, and for protecting the RS485 communication chip inside bus, forward direction is by voltage clamp in 0.7
V, newest bias voltage required between other RS485 chip A, B in bus when for maintaining high level and when bus free, and make
Other absorption pulse transformer rings.
Claims (1)
1. a kind of RS485 bus communication circuit based on transformer, it is characterised in that using CN1, CN2 as standard network interface connector,
RS485 signal A, B pass through the 3rd foot of network interface and the 6th foot, at the beginning of the signal on two-wire bus is connected to pulse transformer by cable
Grade the 1st foot of terminal and the 2nd foot, signal are transferred to secondary side after pulse transformer, and the 3rd foot of pulse transformer is connected to common mode
4th foot of the 1st foot of inductance and the 2nd foot of D1, pulse transformer is connected to the 2nd foot of common mode inductance and the 1st foot of D1, D1's
3rd foot is connected to GND, and pulse transformer secondary side, which is powered on GND, holds C1 and C2, and signal reaches U1 after common mode inductance filters
The 7th foot and the 8th foot, the 8th foot of U1 is connected to Vcc, and C3 is held in power-up over the ground, and the 2nd foot of U1 and the 5th foot are connected to GND, U1's
1st foot, the 3rd foot and the 4th foot are connected to MCU, finally realize the isolation of RS485 communication;Wherein pulse transformer for node every
From;TVS pipe back clamping is in 5V, and for protecting the RS485 communication chip inside bus, forward direction in 0.7 V, uses voltage clamp
Newest bias voltage required between other RS485 chip A, B in bus when maintaining high level and when bus free, and make other
Absorb pulse transformer ring.
Priority Applications (1)
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CN201821003984.9U CN208316749U (en) | 2018-06-27 | 2018-06-27 | A kind of RS485 bus communication circuit based on transformer |
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CN201821003984.9U CN208316749U (en) | 2018-06-27 | 2018-06-27 | A kind of RS485 bus communication circuit based on transformer |
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Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
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CN108737237A (en) * | 2018-06-27 | 2018-11-02 | 浙江禾川科技股份有限公司 | A kind of RS485 bus communication circuits based on transformer |
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Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
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CN108737237A (en) * | 2018-06-27 | 2018-11-02 | 浙江禾川科技股份有限公司 | A kind of RS485 bus communication circuits based on transformer |
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