Source: International supplier author: nanjing university HanKangRong lu macro LiXiaoYong [font: big in small]
Abstract: based on single-chip processor fax information monitoring system design scheme. Introduces the basic principle of three fax communication and procedures, modem choice and utilization as well as the specific monitoring process, etc. The monolithic integrated circuit to the fax machine to send and receive messages for real-time monitoring, and information stored in the monitoring to external fifo chip, in time by the computer equipment read archived.
Keywords: fax modems t.30 protocol
Fax communication is scanning and photoelectric transformation technology is, will the words, pictures, pictures, etc by the still images made wired or wireless channel sent to the end, and in the back of the still images way to communicate. Since the 1970 s, as in the public telephone exchange open file online fax service, fax communications got to develop, become people to one of the principal means of information transmission. Along with the fax the expansion of business, fax information management requirements to increase. This system is to facilitate the management of all kinds of fax to send and receive messages and development, can monitor and send and receive the fax machine, right in and out of the document and record fax fax machine work log, realize the region of the centralized management of the separation of the fax machine.
This system is mainly for document fax machine of the three, can also be compatible type fax machine.
1 file fax machine three communication protocol
Fax machine in the whole file three communication process follow itu-t suggested the t.30 protocol. The t.30 protocol will the fax communication process is divided into five stages, describing how to start and finish, and an end to fax transmission codes. Fax communication process and telephone communication process similar, according to the time of the divided into five stages as shown in figure 1 below.
(1) stage-a call setting up
Call set-up is through the caller dialing, and was called response, in public switched telephone connection is established on the process. The process and phone calls are basically the same. A call or fax response can realize), also can be realized. According to the calling station and was called station using artificial and automatic operation mode of different composition, the t.30 protocol provisions in the corresponding four kinds of operating methods.
(2) stage-a message before b process
This is a fax machine in transmission from a message to the process of the work. This process including performance logo, and can receive orders to send the confirmed, etc. Therefore, the file in the process of three kinds of machine using the following two signal:
Command signals-mark this fax machine condition, the performance, control each other the working state of the fax machine, etc.
The response signal in order–used for signal answer, will receive the order of the fax machine working state after notice to the other.
All of the command signal and the response signal by a binary signals, the binary signals HDLC frame format as shown in figure 2 shows, the frame structure of the fax FCF control field in the transfer is ordered signal and the response signal.
(3) phase c-a message of process and message transmission
Message transmission is transmit a message stage. To ensure the quality of the transmission, in this phase also arranged in a message process, from it control of this phase all signals, such as the message of synchronous signal, error detection and correction, the line monitoring, etc.
(4) stage d-after a message process
After a message is a message of processing process after stage. Start after sending a message to the end of the message transmission, the end is to start report letters results, and wait for the start command, determine the next step how to deal with. Therefore, in this phase the message signal, use end that signal, many pages signal, fax end signals, etc.
(5) stage e-call release
Call by manual or automatic realize release, and will send and receive telephone line routing fax mode switch to telephone communication mode.
2 the system hardware design
The system design, the key is that the choice of modem chip. The system USES the modem chip rockwell is the production of r144efx chip. R144efx chip is in addition to general modems have short training sequence options, HDLC BianXie frame function, the transmit/receive voice way advantages outside, still have other characteristics