JPH0529178B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a communication method applied when a plurality of communication devices connected by a common transmission path transmit and receive data signals via the transmission path. It is related to.

[Conventional technology]

Such a communication method is also called a common bus method,
There are proposals in Japanese Patent Application Nos. 59-211215 and 211216, etc., and in general, a system is established in which one of the communication devices connected to a common transmission path has the initiative, and control is based on this. A method in which each communication device transmits alternately, or a token
A system is adopted in which a signal indicating the granting of the transmission right is exchanged, and only the communication device that has acquired the transmission right performs the transmission.

[Problem to be solved by the invention]

However, in the method of determining who has the initiative, this is necessary and special equipment must be installed, which is expensive, and if a problem occurs in this equipment, the entire communication becomes impossible and reliability decreases. However, in the method of sending and receiving tokens, this takes time, lowers the overall communication speed, and the procedure for sending and receiving tokens becomes troublesome.

[Means to solve the problem]

In order to solve such problems, the present invention
Communication equipment STA ₁ connected to a common transmission path
STA _o , these communication devices STA ₁ to _{STA o} alternately acquire the transmission right, and the communication device that acquired the transmission right
In a communication system in which STAs transmit data via a common transmission path, communication devices STA ₁ to _{STA o}
Communication devices STA 1 to 1 are provided with self-order timers with mutually different set times T _t1 to _{T to} to determine their own transmission right acquisition order, and the communication devices STA ₁ to STA _o
Set up silent timers with fixed set times T _S1 to _{T so that} are different from each other in order to determine their own priorities, and set each silent timer and each sequential timer in response to the common transmission line being in a no-signal state. A communication device STA that has data to be transmitted and whose self-order timer has timed up acquires the transmission right and transmits the data, and while its own silent timer is counting, the communication device STA The communication device
STA ₁ STA _o shall clear the timing of its silent timer, and if it receives transmission data from another while its own self-order timer is counting, the communication device
STA ₁ to _{STA o} shall clear the timing of their self-order timer, and if the timing of the silent timer is not cleared, the communication device STA that owns the silent timer that times up first acquires the transmission right and transmits. If there is data to be transmitted, the data shall be transmitted; if there is no data to be transmitted, dummy data shall be transmitted; and data transmission from the communication device STA that has acquired transmission rights. When the common transmission line goes into a no-signal state due to termination, each silent timer and its own sequential timer whose set time T _t is recalculated according to a predetermined calculation formula are simultaneously started.

[Effect]

Therefore, according to the present invention, when the common transmission path becomes a no-signal state, the silent timer and self-order timer of the communication devices STA ₁ to _{STA o} start simultaneously, and if the communication devices STA 1 to STA o have data to be transmitted and have the data, A communication device whose self-order timer has expired
The STA acquires the transmission right by itself and transmits the data.

In this case, if transmission data is received from another while the own silent timer is counting, or if data is transmitted while the own silent timer is counting, the communication devices STA ₁ to _{STA o} will start counting the silent timer. clear. Moreover, if transmission data from another is received while the self-order timer is counting, the communication devices STA ₁ to _{STA o} clear the time measurement of the self-order timer.

If the silent timer is not cleared, that is, if there is no signal on the common transmission path for a long time, the communication device STA that has the silent timer that timed out first acquires the transmission right and transmits the data to be transmitted. If there is data to be transmitted, the data is transmitted, and if there is no data to be transmitted, dummy data is transmitted.

When the common transmission path becomes a no-signal state due to the completion of data transmission from the communication device STA that has acquired the transmission right, the silent timer of the communication devices STA ₁ to _{STA o} and its set time T _t are set according to a predetermined calculation formula. The self-sequence timer that was recalculated starts at the same time.

〔Example〕

Hereinafter, details of the present invention will be explained with reference to figures showing examples.

FIG. 2 is a block diagram showing the configuration of the control device, which includes a control unit (hereinafter referred to as "MCP") mainly composed of a microcomputer (hereinafter referred to as "MCP") and a memory.
BCT) 1 ₁ and input/output units (hereinafter referred to as IOUs) 2 ₁ to 2 _o each having circuits corresponding to a plurality of analog inputs AI, analog outputs AO, digital inputs DI, and digital outputs DO are connected to the bus line. _1a1 , and by data exchange between _BCT11 and IOU21 _{~ 2o} , the MCP in _BCT11 performs control calculations according to each input AI and DI, and the results are sent to _IOU21 ~2o. It sends out the outputs AO and DO through _o , and performs local control of air conditioning equipment, etc., which are omitted in the diagram.

In addition, multiple BCT1 ₂ to 1 having IOU similarly
_n are connected by a common transmission path 3 ₁ , and transmit and receive data between each other, and
BCT1 _o and beyond are connected to these transmission lines 3 ₂ and the relay unit through REP4, and are connected to BCT1 ₁
~ _1n and _BCT1o , data is transmitted and received between each other, while the main data transmission path 6 from the main control device (hereinafter referred to as MCT) 5 of a large computer etc. to each part is , gateway with relay and time schedule control functions, transmission line 3 ₁ is connected via GW 7, and even if the data transmission speeds of MCT 5 and BCT _{1 1} to 1 _o , etc. are different, GW 7 can relay these mutually. At the same time, if commands from the MCT 5 cannot be received due to a failure in the MCT 5 or the main data transmission line 6, the GW 7 will take over functions such as time schedule control, causing problems in the control operations of the BCTs ₁ to 1 _o , etc. It has become something that does not exist.

Therefore, BCT1 ₁ to 1 _o , etc. perform local control based on the basic control data given from MCT5, and send this status to MCT5. On the other hand, even if data transmission/reception with MCT5 becomes impossible, BCT11 _{~ 1o} etc. perform local control according to commands from GW7, so overall control is possible. No loss of control will occur.

In addition, a hand-held operation display device (hereinafter referred to as HMMI) 8 can be freely connected and attached to the BCT11 _{to 1o} , GW7, etc., and can be connected with a connector.
When HMHI8 is connected, it is connected to transmission lines 3 ₁ and 3 ₂ via the internal circuit, and by sending and receiving data with any unit via this, BCT _{1 1} to 1 _o , etc.
It is also possible to set and change commands, data, and monitor the operating status of the GW7.

In such a configuration, BCT1 ₁ ~ 1 _o , GW
Data transmission and reception between 7 and HMMI 8 is performed in the manner described below with reference to FIG. 1, assuming that these are all equivalent communication devices or STA.

In other words, when turning on the power or setting the initial state, etc.
In response to the simultaneous "START" of the STAs (STA ₁ to _{STA o} ) (time t0 shown in FIG. 1), the silent timers for monitoring no-signal time provided in each STA ₁ to _{STA o} start simultaneously. The silent timers of STA ₁ to _{STA o} have fixed set times that are different from each other to determine their own priorities, provided that the time is longer than the maximum set time for the self-order timer described later.
T _S1 to T _so are determined. In this example, T _S1 ~
The set time T _s of the silent timer increases in the order of T _so , that is, in the order of STA ₁ to _{STA o} .

After each silent timer starts, first, the silent timer of STA ₁ times up (at time t1). In response to the time-up of the silent timer, STA ₁ acquires the transmission right, performs a self-sequence calculation to be described later, and then transmits the data SD1 that it holds. Other STA ₂ ~
STA _o receives the transmission data from STA ₁ , clears its own silent timer, and performs a self-sequence calculation to be described later.

Then, when the transmission of data SD1 from STA ₁ is completed (at time t2) and the common transmission path becomes a no-signal state, STA ₁ to _{STA o} are set as different from each other by the previous self-order calculation. Time T _t1 ~ _{T to}
At the same time, the self-order timer that was requested for is started, and its own silent timer is started at the same time.

At this time, if STA ₁ does not have any data to send, the next set time after the set time T _t1
In response to the time-up of the self-order timer whose T _t2 is the shortest (at time t3), STA ₂ acquires the transmission right, clears its own silent timer, performs the self-order calculation described below, and data
Perform SD2 transmission. Other STA ₁ , STA ₃ ~
STA _o receives the transmission data from STA ₂ , clears its own silent timer and self-sequential timer, and performs self-sequential calculations to be described later.

Then, the transmission of data SD2 is completed (t4
time), if the common transmission path becomes a no-signal state,
STA ₁ to _{STA o} simultaneously start self-sequential timers whose set times T _t1 to _T to have been recalculated as being different from each other through the previous self-sequential calculation, and simultaneously start their own silent timers.

Assuming that the same operation is repeated and each STA has one piece of data to send,
STA ₃ to _{STA o} sequentially acquire transmission rights and send data.
Transmission of SD3 to SDn will be performed.

In addition, in the above, for example, if the common transmission path becomes a no-signal state at time t6 after the transmission of data SD3 ends, and this no-signal state continues for a long time, the STA that has the silent timer that timed out first will That is, the STA ₁ whose silent timer has the shortest set time T _s acquires the transmission right, and if it has no data to transmit at that time, it transmits dummy data.

That is, when STA ₁ to _{STA o} have no data to transmit and all self-order timers time up, the STA with the silent timer that times up first acquires the transmission right. In other words, if there is no data to be sent to STA ₁ to _{STA o} after one round, that is, if there is no urgent data, STA ₁ with the shortest silent timer setting time is given the first priority. The transmission right is always returned to STA ₁ having the first priority.

In the above-mentioned communication system, the set times T _t1 to T _to for each sequential timer are determined by a sequential calculation according to the following equation (1).

T _t = TT×Tw×P ……(1) However, TT: Order of transmission right acquisition (own order) TW: Transmission time for one word of data For example, Tw
= 2.3 msec P: Coefficient determined according to the processing time of the CPU, for example, P = 3 Tw x P: 1 time slot In the above equation (1), the auto-sequential TT is STA ₁ to STA _o
Based on the sender address SA which is fixedly determined according to the connection order etc. of STA ₁
~Determined for each STA _o .

Regarding GW7, HMMI8, and BCT11 _{to 1o} , first, each sender address SA is determined by the following formula.

[GW]

SA=1×4×m...(2) However, m=1, 2...31 [HMMI] SA=4×MA-1+4×MN×m...(3) However, m=1, 2...30/ MN MA: Physical address MN: Number of connected devices [BCT] SA = 2 × PA ... (4) However, PA: Physical address Based on the SA obtained from the above equations (2) to (4),
Find each self-sequence TT using the following formula.

[GW]

When SA≧CA, TT=SA−CA+1 …(5A) When SA<CA, TT=TS _nax −CA+SA+1 …(5B) However, TS _nax : Maximum automatic order [HMMI] When SA≧CA, TT =SA−CA+1 …(6A) When SA<CA TT=TS _nax −CA+SA+1 …(6B) [BCT] When SA≧CA, TT=SA−CA+1 …(7A) When SA<CA TT =TS _nax −CA+SA+1 ...(7B) Therefore, the self-sequential TT obtained from formulas 5A to 7B
By performing the calculation of equation (1) using , the time Tt to be set for each self-order timer is determined.

As a result, the setting time T _t of the self-ordering timer becomes GW
7. HMMI8, BCT1 ₁ to 1 It is determined rationally according to the importance of each _o and the frequency of requests to acquire transmission rights.

In contrast to the above, the set time T _s to the silent timer in FIG. 1 is fixedly determined by the following equation.

T _s = TSmax + SA × Tw × P ... (8) In addition, in Fig. 1, for ease of explanation, each of STA ₁ to _{STA o} has only one sender address SA, and the sender address S.A.
is assumed to increase in the order of STA ₁ to STA _o .

Figure 3 is a comprehensive flowchart of the transmission/reception control status by the CPUs of STA ₁ to STA _o .
It is executed according to "START" in the figure.

That is, after setting Ts of formula (8) to the silent timer configured by the CPU, "silent timer start" 101 is performed, and while "silent timer out?" 102 is N (NO), the transmission line 3 Step 102 and subsequent steps are repeated via N of "Signal Reception?" The content is a global message (hereinafter referred to as GL) for all, a command message (hereinafter referred to as CD) that gives a command to one of them, or a request message (hereinafter referred to as RQ) that requests data transmission to one of them. , or simply a dummy message for synchronization.
Or CD or RQ? ” 113, and if this is Y, perform “auto-order calculation” 114 to calculate TT according to the current address CA added to the received message using equations (1) to (7B), and further,
``Addressed to self?'' 121 is determined based on the destination address code added to the received message, and ``reception processing'' 122 is performed according to Y.
When step 121 is N, "monitor processing" 123 is performed.

On the other hand, if the result in step 102 is Y, the sender can acquire the transmission right, so it changes its own sender address SA to the current address
Then, similar to step 114, auto-sequential calculations are performed.

Next, it checks "Is there data to send?" 133 for itself, and if it is N, performs "dummy message transmission preparation" 141 to maintain synchronization with others, and then "transmission processing" 142. However, if step 133 is Y, the process immediately moves to step 142.

When the execution of any one of the above steps 122, 123, and 142 is completed, it enters the standby state and goes to step 114.
Or setting time Tt based on TT obtained by 132
Sets the self-sequential timer configured in the CPU and performs "Self-sequential timer start" 151, and also performs "Silent timer start" 152 in the same manner as step 101, and returns Y for "Self-sequential timer timeout?" 153. As in step 133, check ``Is there data to send?'' 154, and if this is N, assume that ``Silent timer timeout?'' 155 is N, and check ``Signal received?'' 162 as in step 111. And this is N
During this time, steps 153 and subsequent steps are repeated, and when step 162 becomes Y, "each timer clear" 163 started in steps 151 and 152 is performed, and in step 162 the destination of the received data is "self-addressed". ?'' 164 is determined in the same way as in step 121, and when it is Y, the ``auto-order operation'' 183 is performed and the process returns to step 122, whereas in the case of N in step 164, the ``auto-order operation'' 184 is performed. Go back to step 123.

Also, while step 162 is N, step 155 is Y.
Then, set own sender address SA as the current address CA by "CA←SA" 171, and
“Is there data to be sent?” 172 Check, “Dummy
After performing "message transmission preparation" 173 and "self-sequence calculation" 174, the process returns to step 142.

However, the setting time T _s of the silent timer and the setting time T _t of the automatic timer have a relationship of T _s > T _t , so that step 153 becomes Y before step 155, and step 154 corresponding to this becomes Y. If the check is Y, "Silent timer clear"
After performing step 185 and setting its own sender address SA as the current address CA with "CA←SA" 181, it performs "self-sequence operation" 182 and moves to step 142, so the self-sequence timer times out. Therefore, the transmission right is acquired, and the data to which the current address CA determined in step 181 is added is transmitted in step 142.

As explained above, according to this embodiment, by providing a self-order timer,
This solves the problem of STA not being able to easily send data, and by providing a silent timer, if there is no urgent data, data transmission can be restarted from the communication device STA with a higher priority. This makes it possible to shorten communication idle time and generally shorten the time from the generation of data to be transmitted to the start of transmission.

Furthermore, since STA ₁ to _{STA o} each have equivalent functions, even if one of them fails, the overall function is maintained, improving reliability, and it is not necessary to send and receive special signals to give and receive transmission rights. This improves overall transmission speed.

However, the configuration of Figure 2 can be determined depending on the situation, and in Figure 3, depending on the situation, each step may be replaced with another equivalent step, the order may be changed, or unnecessary steps may be removed. Various modifications are possible, such as the same effect even if omitted.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, transmission rights can be reliably given and received with a simple configuration, and the overall communication speed is improved.
Overall reliability is improved, and remarkable effects can be obtained in various data communications using a common transmission path.

[Brief explanation of the drawing]

The figures show an embodiment of the present invention, and FIG. 1 is a timing chart of the main part showing the acquisition status of transmission rights, and FIG.
The figure is a block diagram of the control device, and FIG. 3 is a flowchart of the control situation. 1 ₁ ~ 1 _o ...BCT (control unit), 1a ₁ ~ 1a _o
...Bus bar, 2, ~2 _o IOU (input/output unit), 3 ₁ ,
3 ₂ ...Transmission line, 8...HMMI (operation display),
T _S1 ~ T _so ... Setting time of each silent timer,
T _t1 ~ T _to ... Setting time of each individual order timer.

[Claims]

1. A loop network in which one control node and a plurality of communication node signal relay sections are arranged on two circular transmission paths whose signal transmission directions are opposite to each other; the control node and the plurality of communication nodes; Each of the signal relay sections has a first input terminal, a first output terminal, a second input terminal, and a second output terminal that respectively correspond to two transmission paths; is in a bypass state in which both the first input/output terminal and the second input/output terminal are internally connected for communication signals, and the control signal generator;
This control signal generator can be connected to the first output terminal or the second output terminal.
By connecting to either one of the output terminals of the , a control signal is sent to the transmission line, and the sent control signal is sent to the corresponding input terminal even after a predetermined period of time (for example, a period slightly longer than the period required for one loop). a switching means for transmitting the control signal from the other output terminal when the input is not input; and a switching means for transmitting the control signal from the other output terminal when the control signal is not input; Until a control signal is input to the input terminal corresponding to the output terminal, one of the other output terminals is internally connected to the corresponding input terminal so that the control signal can pass through, and the output terminal corresponds to one of the output terminals. If the control signal input to the input terminal is earlier than the control signal input to the input terminal corresponding to the other output terminal, the internal connection state is canceled, and vice versa.

Claims (1)

The data transmission shall be performed after acquiring the trust authority, and if it receives transmission data from another while its own silent timer is counting, or if it transmits data while its own silent timer is counting, each of the above-mentioned communications The devices STA ₁ to _{STA o} shall clear the timing of their silent timers, and if they receive transmission data from another while their own self-order timers are counting, each of the communication devices STA ₁ to STA o clears the timing of its silent timer.
STA _o shall clear the timing of its self-order timer, and if the timing of the silent timer is not cleared, the communication device STA that owns the silent timer that timed out first acquires the transmission right and should transmit. If there is data, that data shall be transmitted; if there is no data to be transmitted, dummy data shall be transmitted; and upon completion of data transmission from the communication device STA that has acquired transmission rights. In response to the common transmission line becoming in a no-signal state, each of the silent timers and the individual sequential timers whose set time T _t is recalculated according to a predetermined calculation formula are started simultaneously. A communication method using a common transmission path.