CN103095509A

CN103095509A - Method for quickly testing recommended standard 485 (RS485) bus breakdown

Info

Publication number: CN103095509A
Application number: CN2011103305099A
Authority: CN
Inventors: 周静; 张厚武; 姚凯学; 张勇; 刘光林
Original assignee: GUIZHOU INTELLIGENT CONTROL ENGINEERING RESEARCH Co Ltd
Current assignee: GUIZHOU INTELLIGENT CONTROL ENGINEERING RESEARCH Co Ltd
Priority date: 2011-10-27
Filing date: 2011-10-27
Publication date: 2013-05-08

Abstract

A method for quickly testing a recommended standard 485 (RS485) bus breakdown is characterized by comprising detectors and detection equipment of the detectors for use. The method includes the steps: firstly, enabling the detectors to be installed on each node of the RS485 bus which needs to be detected in a series connection mode, wherein each detector has different addresses and a controller can control multiple detectors; and then enabling the sum of the nodes on the bus to be arranged into N; and next, adopting dichotomy, first using the controller to send a control signal to the detectors at the positions of N/2 bus nodes and cutting the bus at the position of the N/2 bus nodes; and then checking whether the breakdown still exists, if judging that the breakdown occurs at the position of N/2 nodes which are close to a host machine, reusing the dichotomy in the N/2 nodes at present, and by parity of reasoning, until determining a breakdown point.

Description

A kind of method of fast detecting RS485 bus failure

Technical field

The present invention relates to a kind of detection method of fault, just relate to particularly a kind of method for quick of RS485 bus failure.

Background technology

The EIA of Electronic Industries Association works out and has issued the RS-485 standard in nineteen eighty-three, this standard produces for making up the shortcomings such as the RS-232 communication distance is short, speed is low, the characteristics such as RS485 has strong noise inhibition, wide common mode range, with low cost, development difficulty is low, longer transmission distance (can reach 1200m).RS485 has two-wire system and two kinds of wiring of four-wire system, four-wire system can only realize point-to-point communication mode, many employings is the two-wire system mode of connection now, single line in two-wire system RS485 bus is A, another single line is B, and the two-wire system mode is that a master is many from mode, and transmission means is half-duplex, can articulate a plurality of slaves (node) on bus, distinguish by the address between each slave.

The RS485 network has the limitation of itself, and in the situation of plural node control bus or network, some nodes break down if occur at synchronization, will cause the communication failure on whole bus, even cause the RS485 interface to damage.When reality is used, also because user's form of construction work is different, adopt transferring material, device not to expose on an equal basis series of problems, as common mode disturbances, signal reflex etc.At present, the general way that addresses the above problem has following several.

1, disconnect whole RS485 network, detect respectively the input resistance between each node A and B, and then the theoretical input resistance of interface is made comparisons therewith, whether decision problem occurs at this node, and this kind method efficient is very low, and maintenance cost is high.

2, the voltage between each Nodes A, B and ground and A and B in instrumentation test RS485 network, and then with network in theoretical electrical characteristic comparison.This kind method efficient is still very low, can't accurately navigate to the fault place.

In view of this, the present invention proposes a kind of method of fast detecting RS485 bus failure, can improve the efficient that the RS485 bus is safeguarded, reduces the cost of safeguarding.

Summary of the invention

The method of fast detecting RS485 bus failure of the present invention is intended to the bus by wireless network remote detection two-wire system RS485, finds fast fault place and failure judgement type.

The present invention is achieved in that and uses the checkout equipment that includes detector and controller, at first detector is arranged on each node of RS485 bus that needs to detect, then the node sum on bus is made as N, adopt dichotomy, at first use controller to send out control signal to the detector at bus node N/2 place, cut off the bus at this place, check whether fault still exists, if, judging fault appears in N/2 node close to the main frame, continue to use again dichotomy this moment in this N/2 node, by that analogy, until the localization of faults.Like this, find the required number of operations of fault mostly to be log2N time most, lacked much than the N that checks one by one fault is less important.

Checkout equipment of the present invention comprises detector and controller two parts, and detector is connected on each Nodes of RS485 bus, and each detector has different addresses, and a controller can be controlled a plurality of detectors.

The major function of controller of the present invention is to send control signal by wireless network, and receives from the signal in wireless network, then signal is resolved, and shows by display screen.Controller comprises radio receiving transmitting module I, parsing module I and display module, radio receiving transmitting module I is used for receiving the wireless signal of wireless network, then with signal resolution for to order and to pass to parsing module I, maybe will send by wireless network from the order that parsing module I sends; Then parsing module I receives order, and analyzes whether order is the acknowledgement command that detector sends to radio receiving transmitting module I issue an order, if send idsplay order to display module; Display module receives the idsplay order from parsing module I, and shows corresponding content.

The major function of detector of the present invention is receive the signal in wireless network and it is resolved to order, the discernible order of detector is cut-out, conducting RS485 network-bus, read A, B voltage commands, carry out the rear detector of above order and will send answer signal by wireless network.Detector comprises radio receiving transmitting module II, parsing module II, acquisition module and switch module, radio receiving transmitting module II is used for receiving the wireless signal of wireless network, then with signal resolution for to order and to pass to parsing module II, maybe will send by wireless network from the order that parsing module II sends; Parsing module II receives the order from radio receiving transmitting module II, whether then analyze order is cut-out, conducting RS485 network-bus, read one of A, B voltage commands, if cut off, the order of conducting RS485 network-bus sends corresponding control command to switch module, the operating result that returns of receiving key module then; Send corresponding control command to acquisition module if read A, B voltage commands, then receive the operating result that acquisition module returns, receive result after parsing module II return to acknowledgement command to radio receiving transmitting module II; Acquisition module is used for receiving parsing module II and gathers A, the instruction of B magnitude of voltage, to parsing module II return result; Switch module is used for receiving cut-out and the turn-on command that parsing module II controls the RS485 bus, to parsing module II return result.

Description of drawings

Fig. 1 is checkout equipment block diagram of the present invention;

Fig. 2 is the structured flowchart of checkout equipment middle controller of the present invention;

Fig. 3 is the structured flowchart of detector in checkout equipment of the present invention;

The scheme of installation of checkout equipment when Fig. 4 is fast detecting RS485 bus failure of the present invention;

In figure: A is single line in two-wire system RS485 bus, and B is another single line.

Embodiment

The present embodiment is to use the method for the invention and equipment certain parking lot two-wire system RS485 bus used to be carried out the example of fast detecting.

In Intelligent parking lot management system, for whether unloading lot detection is in the use state, a parking lot detector all is installed in each parking stall, the parking lot detector of some is articulated in (the RS485 chip of quantity and employing has relation, is generally 32,64,128,256 or 400) on main frame RS485 bus.

Now hypothesis has 32 parking lot detectors with detector of the present invention to be articulated under same bus, and the 5th parking lot detector RS485 chip damages and make the whole bus can't communication.

The dichotomy that utilizes this method to provide, detecting step is as follows:

(1) with the 16th detector in the controller control bus, make it cut off bus, scan front 16 parking lot detectors by main frame, still can't communication, failure judgement appears in front 16 nodes;

(2) with the 8th detector in the controller control bus, make it cut off bus, scan front 8 parking lot detectors by main frame, still can't communication, failure judgement appears in front 8 nodes;

(3) with the 4th detector in the controller control bus, make it cut off bus, scan front 8 parking lot detectors by main frame, can communication, failure judgement appears in the 5th to the 8th node;

(4) with the 4th detector in the controller control bus, make its conducting bus, with the 6th detector in the controller control bus, make it cut off bus, scan front 6 parking lot detectors by main frame, can't communication, failure judgement appears in the 5th to the 6th node;

(5) read A, the B magnitude of voltage of the 5th and the 6th node, and judge that malfunctioning node damages as the RS485 chip of the 5th node.

This example detection result shows: use the method for the invention and 32 nodes of equipment Inspection, only need 5 detections can find the fault point.

The method of the invention is also applicable to factory's Monitoring and Controlling, electric power remote meter reading etc.

Claims

1. the method for a fast detecting RS485 bus failure, it is characterized in that: use the checkout equipment that includes detector and controller, at first detector is arranged on each node of RS485 bus that needs to detect, then the node sum on bus is made as N, adopt dichotomy, at first use controller to send out control signal to the detector at bus node N/2 place, cut off the bus at this place, check whether fault still exists, if, judging fault appears in N/2 node close to the main frame, continue to use again dichotomy this moment in this N/2 node, by that analogy, until the localization of faults.

2. the method for fast detecting RS485 bus failure according to claim 1, it is characterized in that: described checkout equipment comprises detector and controller two parts, detector is connected on each Nodes of RS485 bus, each detector has different addresses, and a controller can be controlled a plurality of detectors.

3. the method for fast detecting RS485 bus failure according to claim 1, it is characterized in that: detector comprises radio receiving transmitting module II, parsing module II, acquisition module and switch module, radio receiving transmitting module II is used for receiving the wireless signal of wireless network, then with signal resolution for to order and to pass to parsing module II, maybe will send by wireless network from the order that parsing module II sends; Parsing module II receives the order from radio receiving transmitting module II, whether then analyze order is cut-out, conducting RS485 network-bus, read one of A, B voltage commands, if cut off, the order of conducting RS485 network-bus sends corresponding control command to switch module, the operating result that returns of receiving key module then; Send corresponding control command to acquisition module if read A, B voltage commands, then receive the operating result that acquisition module returns, receive result after parsing module II return to acknowledgement command to radio receiving transmitting module II; Acquisition module is used for receiving parsing module II and gathers A, the instruction of B magnitude of voltage, to parsing module II return result; Switch module is used for receiving cut-out and the turn-on command that parsing module II controls the RS485 bus, to parsing module II return result.

4. the method for fast detecting RS485 bus failure according to claim 1, it is characterized in that: controller comprises radio receiving transmitting module I, parsing module I and display module, radio receiving transmitting module I is used for receiving the wireless signal of wireless network, then with signal resolution for to order and to pass to parsing module I, maybe will send by wireless network from the order that parsing module I sends; Then parsing module I receives order, and analyzes whether order is the acknowledgement command that detector sends to radio receiving transmitting module I issue an order, if send idsplay order to display module; Display module receives the idsplay order from parsing module I, and shows corresponding content.