CN108833056B

CN108833056B - Encoding method for priority communication of two fire-fighting buses

Info

Publication number: CN108833056B
Application number: CN201810500316.5A
Authority: CN
Inventors: 曾新民
Original assignee: Jiangsu Grand Intelligent Electric Co ltd
Current assignee: Jiangsu Grand Intelligent Electric Co ltd
Priority date: 2018-05-23
Filing date: 2018-05-23
Publication date: 2021-02-23
Anticipated expiration: 2038-05-23
Also published as: CN108833056A

Abstract

The invention discloses a coding method for priority communication of two fire buses, which is characterized in that when 1 master station and a plurality of slave stations on the two fire buses communicate, the coding method for the priority request report only needs a byte data transmission process, the priority data processing is carried out according to the byte transmission process of 10-100, compared with the communication response speed adopting a conventional polling mode, the response speed is improved by hundreds of times, compared with the design adopting a more complex priority communication protocol, the response speed is also improved by tens of times. The communication coding method provided by the invention can also feed back bus short circuit faults, only one data transmission process is needed at most, the bus faults and bus output protection can be fed back quickly, and the reliability of fire-fighting products is improved.

Description

Encoding method for priority communication of two fire-fighting buses

Technical Field

The invention provides a coding method capable of supporting bus priority communication and quickly feeding back bus short-circuit faults, and particularly relates to a communication coding method suitable for two fire-fighting buses.

Background

At present, the two buses are widely applied in the fire fighting industry, and the characteristics of bus power supply, long communication distance, convenient wiring, strong load carrying capacity and the like are supported. However, the physical layer design (downlink voltage and uplink current) of the two fire buses determines that the communication speed is relatively slow (not more than 9600bps), and in practical application, the number of communication devices on the buses is large, so that the communication speed is slow, when a polling mode is adopted conventionally, the time of critical data response delay may take tens of seconds, and the bus is not suitable for occasions with high response speed requirements, and a complicated priority communication protocol design is adopted, so that the software design is complicated, the workload is large, and the response time also needs several seconds.

Disclosure of Invention

The invention aims to provide a coding method for priority communication of two fire buses, which solves the defects in the prior art.

The technical scheme adopted by the invention for solving the technical problems is as follows:

a coding method for fire-fighting two-bus priority communication adopts 48 standard time slices T1-T48 to form a standard data transmission process, a slave station synchronizes time slice signals by capturing voltage synchronization signals sent by a master station, and the synchronization standard data transmission is triggered from the voltage falling edge at the time of T1, wherein the time sequence of T1 is bus short circuit fault feedback processing, the time sequence of T2 is a priority request processing process mark, the time sequence of T3 is a priority request response mark, and the time sequence of T4 is a data uplink response mark, wherein the priority code uplink process T5-T12 is an 8-bit data uplink time sequence, the data uplink process T5-T13 is an 8-bit data and 1-bit check uplink time sequence, the time sequence of T14-T48 is an uplink process idle time sequence, the data downlink process T5-T8 is a start bit, and the time sequence of T9-T48 is an 8-bit data, a 1-bit check and a;

three voltage signals of VH, VL and V0 are output from the master station to transmit data, wherein the VH high voltage signal transmits idle and is supplied with power by a bus, the VL low voltage signal is response of the slave station and bus fault feedback level 1/3VH, V0 is zero voltage signal output and is used for bus downlink data bit 0, 4T VH voltage is output when the downlink bit is equal to 1 when the bus downlink data is transmitted, 3T VH voltage and 1T V0 voltage are output when the downlink bit is equal to 0, 4T VH and idle signal VH are stopped, and the power supply capacity of the bus is ensured to be more than or equal to 75%;

the slave station on the bus responds to an uplink request and responds to uplink data through a load resistor, the master station receives the bus response and the uplink data through bus current, a diode of a power supply circuit of the slave station takes power in a one-way mode, when the master station sends a VL low-voltage signal, the slave station applies the load resistor R to the bus, the bus current is equal to Ir which is VL/R, VL is lower than the internal voltage of the slave station, the bus current is close to 0 when no bus response exists, if 1 slave station responds, the bus current is equal to VL/R, the VL voltage output of the master station adopts a current-limiting design, and the maximum VL voltage output current is 3-5 times of VL/R;

the master station sends out a V0 signal to mark a priority processing process at T2, the priority request slave station does not answer the priority code any more, the master station waits for finishing all priority processing, and the priority request is reset; and when the master station sends out a VL signal at T1, no slave station responds, and if the bus is in short-circuit fault, the short-circuit current is greater than VL/R, and the bus is fed back to be in short-circuit fault.

The invention has the following beneficial effects:

the encoding method for the fire-fighting two-bus priority communication is used for overcoming the defect that the conventional fire-fighting two buses are not suitable for occasions with higher communication response speed requirements, can enable the fire-fighting two buses to support priority communication transmission, is simple in software design, and is very suitable for application occasions with higher response speed requirements of a fire-fighting system on real-time alarm, fault and the like, and key data response time only needs several milliseconds to hundreds of milliseconds. When 1 master station and a plurality of slave stations on two buses for fire fighting communicate, the communication coding method is adopted, the priority request report only needs one byte data transmission process (48 × T, if T is equal to 125uS, 6MS in total), the priority data processing is carried out according to 10-100 byte data transmission processes (total time is 60-600 MS), compared with the communication response speed adopting a conventional polling mode, the response speed is improved by hundreds of times, compared with the design adopting a more complex priority communication protocol, the response speed is also improved by tens of times. The communication coding method provided by the invention can also feed back bus short-circuit faults, only one data transmission process (48 × T, if T is equal to 125uS, the total is 6MS) is needed at most, the bus faults and the bus output protection are fed back quickly, and the reliability of fire-fighting products is improved.

Drawings

FIG. 1 is a schematic diagram of a voltage falling edge when the output voltage of the master station falls from VH to VL according to the present invention.

FIG. 2 is a flow chart of the fire protection two-bus encoding process of the present invention.

Fig. 3 is a schematic diagram of the main station downstream communication adopting three voltage signals according to the present invention.

Fig. 4 is a circuit diagram of the master and slave stations outputting voltage signals according to the present invention.

Detailed Description

The technical solution of the present invention is further described below with reference to the following embodiments and the accompanying drawings.

The embodiment provides a coding method for priority communication of two fire buses, which comprises the following steps: three voltage signals (as shown in fig. 3) are adopted for master station downlink communication, a VH high voltage signal is used for transmitting idle signals and the master station supplies power to the slave station, the VH high voltage signal is generally 24V-36V, a VL low voltage signal is a master station output level during slave station response and bus short circuit fault feedback, the VL low voltage signal is generally 1/3VH, and a V0 zero voltage signal is a master station downlink data 0 output level. The slave station responds data in a load resistor mode, and the slave station responds when the master station sends a VL low-voltage signal. The supply voltage of the master is VH and when the master transmits a VL low voltage signal, the slave internal diode D1 ensures that the bus current is approximately 0 when no slave is responding. When the slave station has a priority response or a data response, the slave station applies a load resistor R to the bus when the master station transmits a VL low voltage signal, and the bus current is approximately equal to Ir and is equal to VL/R (see FIG. 4). In order to ensure that the slave station is supported to respond and arbitrate preferentially, a current-limiting design is adopted when the master station outputs a VL low-voltage signal, and the maximum current can be designed to be 2-3 times Ir.

In the encoding method, when a master station communicates with a plurality of slave stations, a standard time slice T is provided, a standard data transmission or response process comprises 48 standard time slices T, and the slave stations synchronize time slice signals by capturing voltage synchronizing signals transmitted by the master station, wherein the synchronizing signals are voltage falling edges when the output voltage of the master station falls from VH to VL (as shown in figure 1). The coding modes of data transmission and response are divided into 6 types: as shown in fig. 1, the idle sync code is 1.1, the data downlink code is 1.2, the data uplink code is 1.3, the priority request code is 1.4, the priority processing downlink code is 1.5, and the priority processing uplink code is 1.6, specifically, as shown in fig. 1, for the idle sync code, from the voltage sync signal, the master station transmits a VL voltage signal of 4 × T standard time slices and a VH voltage signal of 44 × T standard time slices; for data downstream encoding, starting from the voltage sync signal, the master station sends a VL voltage signal of 4 × T standard time slices and a bit transfer signal of 44 × T, wherein the bit transfer signal comprises: 1 start bit signal 4 × T, 8 data bit signals 4 × T × 8, 1 check bit 4 × T, and 1 stop bit signal 4 × T, wherein when a transmitted data bit is equal to 1, VH level of 4 × T is output, and when a transmitted data bit is equal to 0, 3T (VH)1 × T (V0) is output, the start bit is fixed to 0, and the stop bit is fixed to 1; for data uplink coding, starting from a voltage synchronization signal, a master station sends a VL voltage signal of 4 × T standard time slices, when the master station sends T4, the master station continues to send the VL voltage signal of 9 × T standard time slices after detecting a response data mark of the slave station, the slave station responds 8-bit data and 1-bit check in the 9 × T standard time slices, the master station reads the response data and the check bits of the slave station while sending the 9 × T standard time slices, and the master station continues to send a VH voltage signal of 35T standard time slices; for priority request coding, starting from a voltage synchronizing signal, a master station sends VL voltage signals of 4 standard time slices, slave stations with priority data reporting requests on a bus send priority reporting requests when the master station sends T3, the slave stations send data uplink requests when T4, the master station continues to send VL voltage signals of 9 standard time slices after detecting the slave station priority data requests and the data uplink requests, all slave stations reporting priority data simultaneously respond to priority data reporting codes in the 9 standard time slices, the master station reads the priority reporting codes of the slave stations (the priority codes are the 'OR' values of all priority reporting slave station codes) while sending the 9 standard time slices, and the master station continues to send VH voltage signals of 35 standard time slices; for the process of processing the slave priority request in the data priority processing downlink and data priority processing uplink behaviors, the master station sequentially transmits T1(VL) and T2(V0) from a voltage synchronous signal, T2(V0) indicates that the master station has entered the data priority processing, the slave station keeps responding to the priority request and does not respond to the priority code, the master station sequentially transmits T3(VL) and T4(VL), when the priority data is downlink, the slave station does not respond at T4, and the master station transmits 44T data which is coded with data downlink. When priority data uplink, the slave station responds to the data at T4, the master station sends 9T (VL) and 35T (VH), the priority requests are coded with the data uplink, no priority request exists at T3(VL), all the priority requests are processed, and the bus shifts to a normal data idle or data transmission process; for the bus short-circuit fault feedback shown in 1.7 in fig. 1, starting from the voltage synchronization signal, the master station sends a T1(VL) voltage signal, when the bus is not short-circuited, any slave station does not respond at this time, the bus current is close to 0 at this time, if the bus is short-circuited, the bus current is much greater than Ir at this time, the master station detects a bus response current I > Ir, marks the bus short-circuit fault, feeds back the bus short-circuit fault, closes the bus output, and restarts the bus function after waiting for a bus reset signal, thereby realizing the bus short-circuit fault feedback and bus protection functions.

If the bus transmission standard time slice T is equal to 125 microseconds, the output voltage VH of the main station is equal to 24V, VL is equal to 8V, V0 is equal to 0V, the response resistance R of the slave station is equal to 100 ohms, the response current I of the slave station is equal to VL/R and equal to 80mA, the output voltage VL of the main station is equal to 8V, 5 times of the current Imax of the normal current is equal to 400mA, the bus current Ic detected by the main station is equal to 50mA, the bus is responded, and otherwise, the bus is not responded. The master station supports a plurality of slave stations to simultaneously respond to a priority request and a logical OR response of the priority code when detecting the bus priority request, and the master station processes the relevant priority request preferentially according to the total priority code. The communication coding adopts 48 standard time slices to form a standard data transmission, T1 is bus short circuit fault feedback, T3 is bus priority request feedback, and T2 is bus priority processing process mark. The maximum feedback delay time of the bus short-circuit fault is 1 standard data transmission process 48T equal to 6 milliseconds, the maximum feedback delay time of the bus priority request is 1 standard data transmission process 48T equal to 6 milliseconds, and the bus priority request processing process is 60 to 600 milliseconds according to 10 to 100 standard data transmission delay time.

The fire-fighting two-bus priority communication coding adopts 48 standard time slices T to form a standard data transmission process, synchronous standard data transmission is triggered from the voltage falling edge at the time of T1, the time sequence of T1 is bus short-circuit fault feedback processing, T2 is a priority request processing process mark, T3 is a priority request response mark, and T4 is a data uplink response mark. The priority code uplink process T5-T12 is an 8-bit data uplink timing sequence, the data uplink process T5-T13 is an 8-bit data and 1-bit check uplink timing sequence, and the data uplink process T14-T48 is an uplink process idle timing sequence. The data downlink process T5-T8(4T) is a start bit, and T9-T48(4T × 10) is 8-bit data, 1-bit checksum, and 1-bit stop bit. The main station outputs three voltage signals to transmit data: VH, VL, V0, VH high voltage signal transmission is idle and bus power, VL low voltage signal is about 1/3VH for slave station response and bus fault feedback level, V0 is zero voltage signal output for bus downstream data bit 0. When the bus descends data, in order to guarantee the power supply capacity of the two buses, 4T VH voltage is output when the descending bit is equal to 1, 3T VH voltage and 1T V0 voltage are output when the descending bit is equal to 0, 4T VH and an idle signal VH are stopped, and the power supply capacity of the buses is guaranteed to be larger than or equal to 75%. And the slave station on the bus responds to the uplink request and responds to the uplink data through the load resistor, and the master station receives the bus response and the uplink data through the bus current. The diode of the power supply circuit of the slave station ensures unidirectional power supply, when the master station sends a VL signal, VL is lower than the internal voltage of the slave station, the bus current is close to 0 when no bus responds, and if 1 slave station responds, the bus current is approximately equal to VL/R. The VL voltage output of the master station adopts a current-limiting design, and the maximum output current of the VL voltage is 3-5 times VL/R, so that the bus communication code is ensured to support a plurality of slave stations to simultaneously answer the priority request and the priority code. The master station issues a V0 signal at T2 to mark the priority process, and the priority requesting slave station no longer responds to the priority code, waits for the master station to complete all priority processes, and requests a reset. When the master station sends a VL signal at T1, no slave station responds, if the bus is in short-circuit fault, the short-circuit current is definitely larger than VL/R, and the bus is fed back to be in short-circuit fault.

The sequence of the above embodiments is only for convenience of description and does not represent the advantages and disadvantages of the embodiments.

Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.

Claims

1. A coding method for priority communication of two fire buses is characterized in that:

the method comprises the steps that a standard data transmission process is formed by adopting 48 standard time slices T1-T48, time slice signals are synchronized by slave stations through capturing voltage synchronization signals sent by a master station, and synchronous standard data transmission is triggered from a voltage falling edge at the moment of T1, wherein the time sequence T1 is bus short-circuit fault feedback processing, the time sequence T2 is a priority request processing process mark, the time sequence T3 is a priority request response mark, the time sequence T4 is a data uplink response mark, the priority code uplink process T5-T12 is an 8-bit data uplink time sequence, the data uplink process T5-T13 is an 8-bit data and 1-bit check uplink time sequence, the time sequences T14-T48 is an uplink process idle time sequence, the data downlink processes T5-T8 are start bits, and the time sequences T9-T48 are 8-bit data, 1-bit check and 1-bit stop bits;