JPH026464B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Technical Field of the Invention The present invention relates to a communication control device that controls data transmission and reception in a polling system.

(b) Prior art and problems In a system in which multiple terminal devices are connected to the main processing unit of a center via a communication control device, polling from the communication control device to the terminal side is performed.
After issuing the signal, the communication control device monitors the presence or absence of data sent from the terminal side. As a means for monitoring this time, a timer is set to a time that exceeds the time required to receive the maximum block of data (defined by the system), and after the polling signal is sent, this timer is started and the timer is set. If no data was received within a specified time, a method was adopted in which it was assumed that there was no response. This conventional method has the disadvantage that it takes time to detect a non-communication state because the timer setting time is long. In order to improve this problem, a method has been adopted in which a second timer for detecting a non-communication state is provided and the non-communication state is detected by detecting the number of consecutive bits of received data. However, although this method enables early detection of the presence or absence of received data, it has the disadvantage that two timers are required and the circuit configuration becomes large.

(c) Purpose of the Invention The present invention has been made to solve the above-mentioned drawbacks, and an object of the present invention is to provide a communication control device that facilitates detection of the presence or absence of received data.

(d) Structure of the invention The present invention is connected to a terminal device via a communication circuit,
A communication control device that receives data with a predetermined maximum block length issued by the terminal device in response to a paging signal, the communication control device including a timer and a first time setting means for setting and activating the first time in the timer. and a second time setting means for setting and activating the timer a second time exceeding the time required to receive data of the maximum block length, and a determining means for detecting the presence or absence of the received data, After transmitting the call signal to one of the terminal devices determined in a predetermined order, the first time setting means starts the timer, and when the timer finishes counting the elapse of the first time. , the determining means determines whether data has not been received or is being received from the terminal device, and if data has not been received, starts transmitting the paging signal to the terminal device next in the order, and the terminal device is receiving data. If so, start the timer by the second time setting means, and after the timer finishes counting the elapse of the second time, transmit the paging signal to the terminal device next in the order. This is a communication control device characterized in that: As described above, the present invention provides one timer for time monitoring, sets a first time in this timer immediately after sending a polling (calling) signal, and determines whether there is received data after this time elapses. However, if data is being received, a second time (time that exceeds the time required to receive the maximum block length) is set in the timer to monitor the reception status. The first time set in the timer is set in consideration of the delay time of the modem and the communication circuit, and is extremely short compared to the second time. If data reception is completed within the first time period, the timer may be stopped at that point and a polling signal may be sent to another terminal device. By doing so, it becomes possible to shorten the detection time of a non-communication state.

(e) Examples of the invention The present invention will be explained below with reference to the drawings. FIG. 1 is a block diagram illustrating one embodiment of the present invention. Terminal devices A to Z in FIG. 1 are connected to a communication control device 2 by a modem (not shown) and a communication circuit 1. The terminal devices A to Z in FIG. The communication control device 2 includes a sub-processing device 3,
It incorporates a local memory 4, a control section 5, and a timer C. The communication control device 2 issues a polling signal P to each terminal device in a predetermined calling order to the terminal devices A to Z.
Although the data D is sent from the terminal Z), the communication control device 2 needs to monitor the time until the data arrives. For this reason, a timer for time monitoring is required, but in the present invention, one timer C can detect received data and detect the end of data reception. In FIG. 1, the processing section 6 issues a polling signal P after clearing the memory section _M1 of the local memory 4, and sets a timer C to a time _T1 . This time _T1 is set in consideration of communication delay as described above, and is a time during which at least the first block (frame) of polling response data on the terminal side can be received. Note that in the embodiment, a time is set during which several frames of response data can be received. When data D is received from a terminal device (for example) A that responded to the polling signal P, each time a byte is received, the length m of the local memory 4 is set in the up-down counter 12, and after incrementing it by 1, the multiplexer 1
The length m+1 is stored in the local memory 4 through 0. When the timer C reaches a predetermined time, the processing section 6 accesses the memory section _M1 of the local memory 4 to read data. If the read data is "0" (length is zero), the data is not being received, so the processing unit 6 sets time T ₁ again in the timer C after sending polling to another terminal device. do. As a result, line monitoring (whether or not received data has arrived) is continued again. On the other hand, if the data read from the memory section _M1 of the memory 4 is not "0", this indicates that data is being received, so the processing section 6 sets the timer C to the time _T2 . This time _T2 is the time that exceeds the time required to receive data of the maximum block length. Therefore, after the time _T2 has elapsed on the counter C, the processing section 6 checks the data (block length) in the memory section _M1 of the local memory 4, thereby detecting the end of data reception.

FIGS. 2 and 3 are time charts explaining the above operation. Figure 2 shows timer C
This is an example of a case where T ₁ is set and no data is received even after this time T ₁ has elapsed. In FIG. 2, the processing unit ₆ in _{FIG .}
After setting it up, start it. this time
At time t ₄ after T ₁ has elapsed, the processing unit 6 examines the memory section M ₁ of the local memory 6 . As shown by the broken line in FIG. 2d, if there is no received data (the length of memory _M1 is zero), the processing unit 6 regards it as a non-response and sends a polling signal _P2 to another terminal device via the transmission line S. At the same time, the time is sent to timer C again.
After setting T ₁ , start it. On the other hand, an example in which received data is detected is shown in FIG.

In FIG. 3, after transmitting the polling signal _P1 at time _t1 , the processing unit 6 sets a time T1 to the timer C and starts the timer _C. Data D from the terminal device in response to the polling signal _P1 arrives at time _t2 as shown in FIG. 3c, and when reception is started, it is stored in the memory at time _t3 as shown in FIG. Part M ₁
Block length BL (numeric data) is written to. When the data in the memory unit _M1 is checked at time _t4 after the set time _T1 of the timer C has elapsed, it is found that data is being received since BL≠0. As a result, the processing unit 6 sets the time _T2 to the timer C (at time _t5 ), and then starts the timer C, as shown in FIG. 3b (at time t5). Since the set time _T2 of timer C is longer than the time to receive data of the maximum block length, it should not be receiving data after the set time _T2 has elapsed, that is, at time _t6 . If the reception has been completed, the processing unit 6 sends a polling signal to the next terminal device in the calling order, as shown in FIG.
_P2 is sent, and timer C is set to time _T1 and started. However, if data is still being received after T ₂ hours, the processing unit 6 determines that it is in an error state, performs the necessary error processing, stops transmission from the terminal device, and then resumes transmission to the next terminal device. Start polling signal transmission. Set time _T1 to timer C
If the relationship between T ₂ and T 2 is selected such that T ₁ ≪ T ₂ , the detection time of received data will be faster, and the time T ₂ will be
Since the size is sufficient to receive data of the maximum block length, there is no possibility of erroneously detecting the end of reception.

(f) Effects of the invention As described above, the present invention simplifies the circuit configuration because only one counter is required for time monitoring, and the time required to detect a non-communication state is short.
This has the advantage of shortening the polling cycle for terminal devices and improving data collection efficiency.

[Brief explanation of drawings]

FIG. 1 is a block diagram for explaining one embodiment of the present invention, and FIGS. 2 and 3 are time charts for explaining one embodiment of the present invention. Reference symbols used in the figures are as follows. 1 is a communication line, 2 is a communication control device, 3 is a sub-processing device, 4 is a local memory, 5 is a control unit, 6 is a processing unit, 7 is a transceiver, 8 is a bus, 9 is a driver, 10 and 11 are multiplexers, 12 and 15 are counters, 13 and 14 are buffers, 16 is a main processing unit, 17 is a main memory, 18 is a common bus, A, Z
is a terminal device, BL is block length data, C is a timer, D is data, _M1 is a memory section where block length data is stored, _M2 is a memory section where address data is stored, P is a polling signal, and R is a S is the receiving line, S is the transmitting line, T ₁ and T ₂ are the set times of the counter C, and t ₁ , t ₂ , t ₃ , t ₄ and t ₅ are the times.

Claims (1)

[Scope of Claims] 1. A communication control device that is connected to a terminal device via a communication circuit and receives data with a defined maximum block length issued by the terminal device in response to a paging signal, comprising: a timer; The first step is to set the first time on the timer and start it.
a second time setting means for setting and activating a second time in the timer that exceeds the time required to receive data of the maximum block length; and a determining means for detecting the presence or absence of the received data. After transmitting the paging signal to one of the terminal devices determined in a predetermined order, the first time setting means starts the timer, and the timer measures the passage of the first time. When the terminal device is finished receiving data, the determining means determines whether data has not been received or is being received from the terminal device, and if no data has been received, it starts transmitting the paging signal to the next terminal device in the priority order. , if data is being received, start the timer by the second time setting means, and after the timer finishes counting the elapse of the second time, the call is made to the next terminal device in the priority order. A communication control device that starts transmitting a signal.