JP3446870B2 - Signal transmitter with communication function - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [0001] BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the detection of a physical quantity such as a flow rate.
Output, signal processing, and current signal to the load side via the transmission line.
And a digital signal is superimposed on this current signal.
And a signal transmitter having a communication function of communicating with each other.
In particular, communication signals or transmission lines transmitted from transmission lines
Noise other than the communication signal mixed in from above and from the signal converter
Communication that has been improved so that it does not conflict with directly transmitted communication signals
The present invention relates to a signal transmitter having a communication function. [0002] 2. Description of the Related Art FIG. 7 shows a conventional signal transmission having a communication function.
FIG. 3 is a block diagram showing a configuration of a container. Signal transmission in this case
3-wire signal transmitter that outputs a flow pulse as an example of a transmitter
Is shown. 10 converts physical quantities such as flow rate into electrical signals.
The signal transmitter 10 is a signal transmitter for transmitting the signal.
Terminal T from the power supply 11 via the load 12₁, T_TwoContact with
The power is supplied to the signal transmitter 10 from here.
The DC power supply 11 and the load 12 are connected to the receiving instrument located far away.
Are located. An electric signal is output from a signal transmitter 10 at an output terminal.
T₁, T_TwoTransmission line L connected to₁, L_TwoThrough analog
Current signal I_LTo the load 12 and the flow rate is
Detecting analog voltage changes occurring at both ends of 12
Is obtained by The current signal I_LCorresponds to the flow range, for example
4 to 20 m by the signal transmitter 10 set in the range
A is converted to the unified current of A and transmitted to the load 12 side.
For example, a 4-digit digital display is displayed on a built-in monitor. In this case, for example, the flow range is changed.
Or change various parameters or monitor
Is convenient if it can be operated from outside the signal transmitter 10
It is. For this reason, a c functioning as a first communication terminal.
If necessary, connect the transmission line L₁₁,
L_{twenty one}And a handheld transmitter connected to the signal transmitter 10.
A dedicated data communication function with the terminal 14
From the terminal 14 to the signal transmitter 10.
Transmit digital data such as data changes. [0007] The signal transmitter 10
Is configured as follows. SNR is the flow rate
Is a detector (sensor) that detects
The converted measurement signal is supplied to the analog / digital converter A
/ D is converted to a digital signal by the microprocessor μ
P₁Through memory MEM₁Random access note in
It is stored in the part. [0008] Microprocessor μP₁Are those cases
Memory MEM using stored digital signal₁For example
By the operation procedure written in the read-only memory part
Performs a predetermined operation such as linearization, and decodes the result.
Output circuit OPC via digital / analog converter D / A
Output to Output circuit OPC is digital / analog conversion
The voltage signal converted into an analog signal by the device D / A is 4 to 2
0 mA unified current signal I_LTo the transmission line L₁,
L_TwoTransmitted via. The output circuit OPC is
Current signal I transmitted from the source 10 side_LUsing part of
The power supply for the internal circuit of the signal transmitter 10 is generated. [0010] IFC₁Is with the handheld terminal 14
Interface for data communication and transmission
Line L₁, L_TwoAnd microprocessor μP₁Connected between
Have been. Output terminal T₁And T_TwoTransmission line connected to
L₁, L_TwoDigital signal sent to the common potential point CO
M and summing amplifier Q₁Is applied to one end of the input end of
Terminal T via no serial / parallel converter_ThreeParallel via
Microprocessor μP as signal₁Is transmitted to Conversely, the microprocessor μP₁De from
Digital data is transmitted to the output circuit OPC as a serial signal.
The output circuit OPC is an analog 4 to 20 mA current signal.
Issue I _LTo the transmission line L₁, L_TwoTo the load 12 side via
Sent out. Further, a failure or the like occurs in the signal transmitter 10.
Interface IFC₁In
Summing amplifier Q₁T connected to the other end of the input end of_FourSet
And a terminal T connected to the common potential point COM._CWith
A second similar to the handheld terminal 14 for maintenance in between
Handheld terminal 15 that functions as a communication terminal
Connect to perform on-site parameter changes
I'm trying. The microprocessor μP₁Calculated by
The digital flow signal obtained is the interface IFC₁
Terminal T_FiveSignal in parallel / serial converter P / S via
Is converted into a field effect transistor Q_TwoApply to gate
Is done. Field effect transistor Q_TwoIs the DC power supply 1
1 and pull-up resistor 16, terminal T₆Through the field effect
Transistor Q_TwoOpen collector connected to the drain of
Field effect transistor Q_TwoGate of
Pulse signal Q corresponding to the signal applied to_PThe load
Terminal T arranged on the side₇And T₈Output between Next, the inside of the handheld terminal 14 will be described.
The configuration will be described. SER operated by operator
This is a setting device, which has a built-in monitor.
Mode change to switch between B tone and span tone, model request,
Change display resolution, change range, detect abnormalities, or
Current signal I_LMake various settings or requests such as displaying the value of
Can be ΜP_TwoIs a microprocessor, for example
If the data from the setting unit SER is input,
_TwoAccording to the processing procedure stored in the
C_TwoA digital signal to the signal transmitter 10 via the
You. The microprocessor μP_TwoIs a signal
The response data from the transmitter 10 is transferred to the interface IFC_Two
Through memory MEM_TwoTo the memory ME
M_TwoDecrypt this according to the processing procedure stored in
Is displayed on the monitor of the device SER. [0019] SUMMARY OF THE INVENTION However, the above
Such a signal transmitter 10 includes a handheld terminal 14.
Communication signal sent from the
Noise other than the transmission signal and the terminal T inside the signal transmitter 10.
_FourSent from the handheld terminal 15 connected to
If the same communication signal is output in conflict with the
There is a problem that I can't trust. As a result, the parameters of the signal
Even if you try to adjust the data
Do not instruct the Null 14 to stop transmitting in any way
Causes a problem that parameter adjustment etc. cannot be performed.
You. [0021] The present invention solves the above problems.
The main solution to this problem is to detect physical quantities and
Transmits current signals related to physical quantities to loads via transmission lines
And superimpose a digital signal on this current signal for communication.
Communication with a microprocessor that communicates with the terminal
A signal transmitter having a communication function,
Transmitted from the first communication terminal to the signal transmitter.
One communication signal and a second communication directly connected to the signal transmitter
Identifying the second communication signal transmitted from the terminal and
To transmit the data to the microprocessor.
An interface circuit, wherein the interface circuit comprises:Said ma
Initialized by the microprocessor, receiving the second communication signal
Flip-flop that detects whether or not it is
The microprocessor detects the state and sets the state.
A first logic element for blocking or passing the first communication signal;
According to the output of the first logic element, the second communication signal or
A second logic element for controlling passage of the first communication signal;With
It is something to be prepared. [0022] BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described.
This will be described with reference to the drawings. FIG. 1 shows the structure of one embodiment of the present invention.
It is a block diagram showing composition. The conventional signal shown in FIG.
Parts that have the same functions as the
The description will be appropriately omitted. Also signal for the present invention
A three-wire signal transmitter will be described as an example of the transmitter.
You. The signal transmitter 17 includes a detector SNR, an analog
Analog / digital converter, digital / analog converter
D / A, output circuit OPC, etc.
Same as transmitter 10, but with memory MEM₁Is the memory M
EM_ThreeThe microprocessor μP₁Is a microprocessor
ΜP_ThreeAnd the interface circuit IFC₁Is an interface
Ace circuit IFC_ThreeHas been changed respectively. This memory MEM_ThreeHas a memory MEM₁When
Contains arithmetic programs of different contents.
Interface circuit IFC_ThreeIs also different, so my
Croprocessor μP_ThreeThe operation by
It is the content of the calculation. First, the interface circuit IFC_ThreeWithin
The configuration will be described. Microprocessor μP_Threeof
Transmission port T_R2Communication signal S transmitted from_M1
And output terminal T₁Communication signal S transmitted from_L1
Is the NOR gate Q functioning as the first logic element_ThreeInput
Entered at the end. On the other hand, from the handheld terminal 15 to the end
Child T_FourCommunication signal S output via_H1And the Noah gate
Q_ThreeThe communication signal obtained at the output terminal of the second logic element
Functioning as a NOR gate Q_FourIs input to the input terminal of
Microprocessor μP from output end_ThreeReceiving port R of₁To
Has been output. The data terminal D of the flip-flop FF is
Source + V_DIs held at high level H by
The lock terminal CK has an end from the handheld terminal 15
Child T _FourCommunication signal S output through_H1Mark
Has been added. Communication signal S_H1Data edge in synchronization with the rising edge of
The logic data obtained at the output terminal Q corresponding to the logic level of the child D
Data is microprocessor μP_ThreeReceiving port R of_TwoOutput to
Have been. Further, the clear end of the flip-flop FF
The child <CLR> (<> means inversion)
Processor μP_ThreeTransmission port T_R1Clear signal CR from
Is sent as needed. The microprocessor μP_ThreeSending port
T_R3Digital signal output to output circuit OPC from
S_D1Is branched to a terminal T₉, Amplifier Q_FiveIn Impedance
Is converted and the handheld terminal 15 is connected.
Terminal T_FourSent to Next, the signal transmitter configured as described above
17 microprocessors μP_ThreeTo the communication functions performed by
The flowcharts in FIGS. 2, 3, 4, 5, and 6
It will be described using FIG. FIG. 2 is a table for controlling a task selection flow.
FIG. 3 is a flowchart showing a procedure for selecting a disk, and FIG.
Flowchart and diagram showing the interrupt procedure for performing a software interrupt
4 is a flowchart showing a conflict determination procedure for determining a communication conflict.
FIG. 5 shows a hardware interrupt for holding a state.
FIG. 6 is a flowchart showing a one-second task, and FIG. 6 is a communication lock.
Shows a 250mS task that performs a hard interrupt for release
FIG. Task selection procedure, interrupt procedure, conflict
Discrimination procedure, 1 second task, and 250mS task
Is a memory MEM_ThreeIs stored in a predetermined area of
Microprocessor according to system clock not shown
Ssa μP_ThreeEach program is executed under the control of. First, the task selection procedure shown in FIG.
The execution is started from the in-program. In step 1
Initial processing is performed, but here the microprocessor
μP _ThreeIs the transmission port T_R1From the clear signal CR (low
Level L) is set to the clear terminal <CL of the flip-flop FF.
R> to set its output terminal Q to low level L,
After that, the state is set to the high level H and the communication standby state is set. Next, the microprocessor μP_ThreeIs the sending port
T_R2Is set to low level L and NOR gate Q_ThreeEntering
One end of the force end is set to low level L, and
The initial processing ends. Thereafter, the process proceeds to step 2. Steps
In 2, cut multiple tasks according to their weight
The task bit to be changed is determined.
Task related to communication, 250ms task
H, the one second task will be described. Memory MEM_ThreeIn, for example, 16 bits
Task selection area is provided, for example, bit 1
Stand up for communication task, bit 2 for 250mS task
If the bit 4 is set, the task shifts to the 1-second task. Of these, the communication task is based on the arrival of a communication signal.
250ms task and 1 second task
Hardware by elapse of predetermined time by counting of built-in counter
Each is executed by an interrupt. Communication task, 250 ms task, or 1
Every time a second task is executed, the status is returned via the return path.
Return to Step 2, where the task selection in the task selection area is
A selection is made and the selected task is performed. Since then,
Repeat this. Next, the operation when the communication task is selected
Will be described. First, if there is communication, the software
Jam occurs (step 1 in FIG. 3) and communication data is received
Memory MEM_ThreeIs stored in the specified area.
In this case, it is determined whether the reception of the communication data has been completed.
Step 3 is executed. In step 3, reception of communication data is completed.
If there is, the process proceeds to step 4 and the communication
Set bit 1 to select the disk, or
If so, keep that bit and go to step 5
, That is, the return path shown in FIG. In step 3, reception of communication data is completed.
If not, return to step 5, ie as shown in FIG.
Move to Return path and execute the communication task shown in Fig. 2 again
Until reception of communication data ends in step 3 of FIG.
Executed in Therefore, the reception of communication data has been completed.
Then, the task bit is bit 1, that is, the communication task
Will be selected. Next, processing when a communication task is selected
Will be described with reference to FIG. Step 1 in FIG.
It is determined whether the communication data is normal. concrete
Has a start bit and a stop bit,
Or, check whether the parity check is normal.
Disconnection is made. When there is an error (Y), Re shown in FIG.
The route is shifted to the turn route, and steps 1 to
Communication data is received according to the flow shown in Step 5.
No, the process returns to the communication task of FIG. When there is no error (N), the step shown in FIG.
Go to step 2. In this step 2, the digital signal is
From terminal 15 to terminal T_FourSent out via
Or the transmission line L₁, L_TwoSent out via
Is determined. The data terminal D of the flip-flop FF is
Since it is held at level H,
If there is digital communication from the null 15, start it up
The logic level of the output terminal Q is high level
It becomes H. Microprocessor μP_ThreeIs the
R_TwoCheck the logical level of the
Handheld when it detects that the
That the digital communication has been performed from the
Knowing, step 3 was reached and the microprocessor μP_ThreeIs
Transmission port T_R2Digital signal S output from_M1The high
Hold at level H. Thus, the NOR gate Q_ThreeInput end of
Is held at a high level H, so that the NOR gate Q
_ThreeOutput terminal is fixed to low level L, and the handheld
Transmission line L from the terminal 14 side₁, L_TwoEntered via
Communication signal S_L1Is shut off. Thus, the NOR gate Q_FourOf the input end of
One end is fixed at low level L, so
Communication signal S output from the terminal 15_H1Is Noah
Q _FourThrough the microprocessor μP_ThreeReceiving port
R₁Received at. Next, in step 2, the micropro
Sessa μP_ThreeIs the receiving port R_TwoLogic level is low level
L, the transmission line L₁, L_TwoFrom the communication signal S_L1Is transmitted
Assuming that the
Processor μP_ThreeTransmission port T_R1Clear signal CR from
(Low level L) to the clear terminal of flip-flop FF
<CLR> to change the logic level of the output terminal Q to low level.
To L. In this state, the microprocessor μP_Three
Is the transmission port T_R2Digital signal S output from_M1The
-Since the level is set to L, the transmission line L₁, L_TwoCommunication from the side
Communication signal S_L1Is Noah Gate Q_ThreePass through Noah Gate Q_Fourof
Output to one end of the input end. Also, the hand-held terminal 15
Communication signal S_H1There is no, so it is low level L,
Therefore, the communication signal S from the handheld terminal 15
_L1Is Noah Gate Q_FourThrough the receiving port R₁Received by
You. After the above processing, the process proceeds to step S5.
In step 5, the timer set time for the one-second task described later
Set the variable tim. After this setting, step 6
To the microprocessor μP_ThreeIs the received communication
No. S_H1, S_L1Decrypts and executes the contents of transmission port T_R3To
Communication signal S via_D1Output circuit OPC and terminal T _Four
Output to Next, the one-second task shown in step 5 of FIG.
Will be described with reference to FIG. This one second task is in state
Performs a hard interrupt independently of communication to manage retention
Specifically, step 3 in FIG.
The time for maintaining the logic level of 4 is set. In step 1 of FIG. 5, step 5 of FIG.
In the counter as the variable tim
Assuming that the period has been set, determine whether this content is zero
Is executed every second, and if it is zero, the process proceeds to step 3,
If not zero, go to step 2 and reduce 1 second here
Calculate. If the result is zero, proceed to step 3
If not, return to Return and repeat again. Step 3 is performed when the value set in the counter is set.
Since the time is up, the first time shown in step 1 of FIG.
Execute the process to return to the initial state, shift to Return, and repeat
Will be returned. In this case, T_R1Once to the low level L,
After that, change to high level H to cancel the locked state,
In standby mode. Next, the 250 second task shown in FIG.
explain. This 250-second task is used in the initial state.
Q_ThreeInput terminals of both are low level L and NAND gate
Q_ThreeWhen the output of the
Q_FourOutput is fixed to low level L, and handheld
Communication signal S from terminal 15_H1Is the receiving port R₁To
Performs processing to avoid input loss.
is there. Specifically, the microprocessor μP
_ThreeHowever, the hardware is divided every fixed period, for example, every 250 ms.
And receive port R_TwoCheck the status of this
If the level is H,
Communication signal S_H1Communication is being carried out by
And the transmission port T_R2Is high level H (step 2)
Transmission line L₁, L_TwoCommunication signal S from_L1The NOR gate Q_Three
And if the signal is low level L, the communication signal S_H1by
Return as it is because there is no communication
Perform processing to shift to. After this, repeat this
Run. Further, in FIG.
ΜP_ThreeDetects and measures the flow rate with the detector SNR.
Flow rate calculation, and the flow rate signal is converted to analog data.
To the load 12 as a current signal of 4-20 mA
However, in addition to this, the flow pulse signal P_fAs terminal T₈, T
₇Sometimes you want to output to In such a case, the microprocessor μ
P_ThreeOutputs the flow signal to the terminal T_FiveThrough the parallel / serial converter P
/ S via the field effect transistor Q_TwoOn / off
Terminal T₈, T₇To the flow pulse signal Q_fIs output. In this case, the transmission line L₁, L_TwoTransmission distance
Is short and the line resistance R_LLWhen is small,
Since the generated pulse voltage is small, the transmission line L₁, L_TwoTo Han
Communication signal S transmitted from the dock terminal 14_L1Is
This pulse voltage has little effect and works without any problems.
You. [0062] The present invention has been described specifically with the embodiments.
According to the present invention, a first communication terminal connected to a transmission line
Communication signal sent to signal transmitter and signal transmitter
Communication transmitted from a second communication terminal directly connected to
Signals and transmit one of them to the microprocessor.
To avoid communication conflicts,
Communication troubles that occur during maintenance
There is a merit that can be. Also, the second communication terminal
When using it, make sure that no noise other than communication signals
To perform on-site maintenance and inspection.
As a result, quick and accurate on-site adjustment is possible.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing a configuration of one embodiment of the present invention. FIG. 2 is a flowchart illustrating a task selection procedure for controlling the flow of task selection. FIG. 3 is a flowchart illustrating an interrupt procedure for performing a software soft interrupt; FIG. 4 is a flowchart illustrating a conflict determination procedure for determining a communication conflict. FIG. 5 is a flowchart showing a one-second task for performing a hard interrupt for holding a state. FIG. 6 shows a case where a hardware interrupt for communication lock release is performed.
It is a flowchart figure which shows a 50mS task. FIG. 7 is a block diagram showing a configuration of a conventional signal transmitter. [Description of Reference Numerals] 10, 17 signal transmitter 11 DC power supply 12 load 15 handheld terminal SNR detector MEM _1, MEM _2, MEM ₃ memory μP _1, μP _2, μP ₃ microprocessor IFC _1, IFC _2, IFC ₃ interface circuit FF flip-flop

──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Hirohide Tsutsui 2-9-132 Nakamachi, Musashino City, Tokyo Inside Yokogawa Electric Corporation (56) References JP-A-6-161521 (JP, A) JP Hei 6-150183 (JP, A) Special table Hei 3-502996 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G08C

Claims (1)

(57) Claims 1. A physical quantity is detected, a current signal related to the physical quantity is transmitted to a load via a transmission line, and a digital signal is superimposed on the current signal to communicate with a communication terminal. In a signal transmitter having a communication function equipped with a microprocessor that communicates with each other, a first communication signal transmitted from the first communication terminal connected to the transmission line to the signal transmitter is directly connected to the signal transmitter. An interface circuit for identifying a second communication signal transmitted from the second communication terminal and transmitting one of the signals to the microprocessor , wherein the interface circuit includes a microprocessor.
Initially set to detect whether or not the second communication signal is received
A flip-flop and the microprocessor
The sensor detects and sets the state and cuts off the first communication signal
Alternatively, the first logic element to be passed and the first logic element
Output of the second communication signal or the first communication signal
And a second logic element for controlling passage.
A signal transmitter having a communication function to perform.