CN104007694A - Multi-point communication digital indicator for PLC switching value output driving - Google Patents
Multi-point communication digital indicator for PLC switching value output driving Download PDFInfo
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- CN104007694A CN104007694A CN201410230494.2A CN201410230494A CN104007694A CN 104007694 A CN104007694 A CN 104007694A CN 201410230494 A CN201410230494 A CN 201410230494A CN 104007694 A CN104007694 A CN 104007694A
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Abstract
The invention discloses a multi-point communication digital indicator for PLC switching value output driving. Hardware of the multi-point communication digital indicator is composed of a power source, a CPU, an LED Nixie tube, a driver of the LED Nixie tube and a serial data receiving circuit. A DC/DC converter of the power source is LM2596, the CPU is PIC16F873, the Nixie tube is CA5461, segment codes of the Nixie tube are directly driven through an I/O port of the CPU, current limiting is realized through a resistor, and bit codes of the Nixie tube are driven through an audion 9012. An MCT6 high-speed optical coupler is used in the serial data receiving circuit for realizing level conversion and enhancing anti-interference capacity. Software realizes time sequence and data receiving and displaying functions needed by the digital indicator. The multi-point communication digital indicator for PLC switching value output driving has the advantages that transmission and displaying of data, to be displayed, of a PLC system and multiple digital indicators can be realized simply through two-point switching value output of the PLC system, therefore, design of such type of PLC systems with multiple parameters to be displayed is simplified, the maintainability is enhanced and the cost is lowered.
Description
Technical field
The invention belongs to automation instrument technical field, relate to a kind of multi-point digital displaying meter driving towards the output of PLC switching value.
Background technology
Programmable controller (PLC), industrial computer (being mainly IPC), intelligent control instrument and Distributed Control System (DCS) (DCS)/field bus control system (FCS) are the four large class opertaing devices that industrial automation is conventional, wherein PLC relies on its high reliability and ease for use, being most widely used in industrial automation engineering.Middle-size and small-size PLC system side overweights logic control, generally with indicating lamp display mode signal.Big-and-middle-sized PLC system has merged the various functions such as logic control, sequential control and process control, generally using computing machine and touch-screen as display device.But under many circumstances, be limited to the requirements such as the rugged surroundings factors such as high temperature, high humidity, many dust and the demonstration of many places, cost control, digital display meter remains the important display device of PLC system, in PLC system, obtains a wide range of applications.
The existing digital displaying meter of PLC system generally has two kinds of implementations, and one is based on field bus communication agreement, and it two is digital displaying meters based on PLC switching value output point.
(1) Fieldbus Based digital displaying meter
Along with control system develops to open system, big-and-middle-sized PLC, by articulating or install all kinds of fieldbus module or adapter, can support all kinds of fieldbus.Adapt therewith, digital displaying meter can only show with certain fieldbus and PLC the transmission of data.Because global field bus protocol standard is not completely unified, occurred the standard for Fieldbus of the main flows such as FF, ProfibusDP, Lonwork, DeviceNet, Interbus, CC-Link, WorldFIP the general layout of depositing, Fieldbus Based all kinds of PLC digital displaying meters are only supported a certain class fieldbus.
(2) digital displaying meter based on PLC switching value output point
This class digital displaying meter does not need PLC that specific hardware configuration and software support are provided, every digital displaying meter need to take two switching value output points of PLC, two switching value output points of PLC system are used separately as to data-signal and clock signal, and PLC gets final product transmitting display data according to the sequential of digital displaying meter agreement.When use, every digital displaying meter can take separately 2 switching values outputs of PLC system, also can n platform digital displaying meter takies (n+1) some switching value output of PLC system, now many digital displaying meter common clock signals.
There is following defect in prior art:
1. Fieldbus Based all kinds of PLC digital displaying meter is only supported a certain class fieldbus, lacks versatility, and user is restricted in the time selecting spare part.PLC system is if the digital displaying meter of use based on a certain class fieldbus requires user must select the PLC system of supporting such fieldbus; Or by increasing adapter or module so that corresponding field-bus interface to be provided, cause user's PLC system cost to increase.
2. the digital displaying meter based on PLC switching value output point need to take PLC system the output of 2 switching values or n platform digital displaying meter at least take the output of n+1 point switching value, are applicable to require the occasion of a small amount of parameter of demonstration.Many when the parameter that requires to show, when geographic position relatively disperses, the switching value output point that now needs to take PLC system is too much, and the communication line of layout is too much, thereby causes the complicated of PLC system, has reduced the maintainability of system.
Summary of the invention
In order to overcome the defect existing in prior art, the present invention proposes a kind of multi-point digital displaying meter driving towards the output of PLC switching value, only can realize the display data transmissions of PLC system and Duo Tai digital displaying meter with 2 switching value outputs of PLC system, and show data or the parameter of PLC system by charactron, simplify the design of PLC system, strengthen maintainability, reduced cost.
Its technical scheme is as follows:
A kind of multi-point digital displaying meter driving towards the output of PLC switching value, its hardware is by power supply, CPU, LED charactron and driving thereof, Serial data receiving the electric circuit constitute, the DC/DC transducer of power supply is LM2596, CPU is PIC16F873, charactron is CA5461, the segment encode of charactron directly uses the I/O mouth of CPU to drive, and by resistance current limliting, the bit code of charactron is used triode 9012 to drive.Serial data receiving circuit uses MCT6 high speed photo coupling to realize level translation and strengthens interference rejection ability, and realizes the transmission that shows data by distinctive sequential.
Beneficial effect of the present invention is, can simplify the design that has multiparameter to show a class PLC system of demand, the distribution that many digital displaying meters can be realized by user installation multiparameter on different physical locations shows, many digital displaying meters that connect PLC system only take two output point, without any agreement support.
Brief description of the drawings
Fig. 1 is the mutual contact mode figure of PLC system and multi-point digital displaying meter;
Fig. 2 is serial transmission address information and the special sequential chart that shows data;
Fig. 3 is multi-point digital displaying meter hardware circuit;
Fig. 4 is the process flow diagram of Serial data receiving program;
Fig. 5 shows refurbishing procedure process flow diagram.
Embodiment
Below in conjunction with the drawings and specific embodiments, technical scheme of the present invention is described in more detail.
The mutual contact mode of 1.PLC system and multi-point digital displaying meter
Take the mutual contact mode shown in Fig. 1.PLC system and the interconnection of Duo Tai digital displaying meter only need the switching value of 2 transistor output types that use PLC system, are used separately as data signal line and clock cable.The switching value output high level (logical one) of PLC system is 24V ± 20%, and low level (logical zero) is 2V ± 20%.Meet the most frequently used 24V power-supply system of industrial application, use 24V logic significantly to promote the anti-interference thresholding of flogic system.
The data transmission sequential (communication protocol) of 2.PLC system and multi-point digital displaying meter
PLC system is pressed the sequential serial transmission address information shown in Fig. 2 and is shown data.Complete Frame shows that by beginning flag, 8 bit address, 16 data and end mark (optional) form.PLC system sends address and shows data by this sequential serial, and digital displaying meter is according to these sequential serial received address and data.
Transmission starts: clock cable is high level, and the negative saltus step of data signal line starts the transmission of a frame information.
The transmission of address and demonstration data: bit address information or a data message transmitted in the positive transition on clock cable.Address information is 8, shows that data message is 16 (4 binary-coded decimal or radix point information that show for data).Show that data encoding is in table 1.
Table 1 shows data encoding
| Scale-of-two | Sexadecimal | Show | Remarks |
| 0000?0000?0000?0000 | 0000 | 0000 | Show data |
| 0000?0000?0000?0001 | 0001 | 0001 | Show data |
| …… | …… | …… | …… |
| 1001?1001?1001?1001 | 9999 | 9999 | Show data |
| 1111?0000?0000?0000 | F000 | XXXX | Radix point is at lowest order (not showing) |
| 1111?0000?0000?0001 | F001 | XXX.X | Radix point is at inferior low level |
| 1111?0000?0000?0010 | F002 | XX.XX | Radix point is in an inferior high position |
| 1111?0000?0000?0011 | F003 | X.XXX | Radix point is in most significant digit |
End of transmission (EOT): clock cable is high level, and the positive transition of data signal line finishes the transmission of a frame information, end of transmission signal is option.Digital displaying meter detects after the start signal of a frame information, 8 bit address to subsequent transmission and 16 bit data (showing data or radix point information) are counted, count down to 24 and represent to have transferred a frame information, digital displaying meter transfers to continue to monitor start signal.If monitoring end of transmission signal, digital displaying meter is received the start signal that just continues to monitor next frame information after end of transmission signal.
3. digital displaying meter hardware design
The hardware of digital displaying meter is by power supply, CPU, LED charactron and driving thereof, Serial data receiving the electric circuit constitute, as shown in Figure 3.
Power circuit: use LM2596 to realize the conversion of 24V to 5V, allowing input voltage is 16V～28V, has wider supply voltage input range, meets 24V industrial power power demands.
CPU: mainly complete the task such as data receiver and demonstration for PLC provides the multi-point digital displaying meter of parameter display function, to processing power require relatively low, therefore 8 micro controller or the single-chip microcomputer of selecting main flow, the present invention selects the PIC16F873 of Mirochip company.
The I/O mouth of charactron and driving circuit thereof: PIC16F873 has the driving force of 25mA, therefore can use the I/O mouth line of single-chip microcomputer directly to drive the segment encode of charactron, and bit code drives by triode 9012.
Serial data receiving circuit: realize the conversion of 24V logic level to 5V logic level by photoelectrical coupler.The switching value output of PLC system is isolated itself, and optocoupler herein changes serial data signal and serial clock signal into current drive-type by voltage driven type, to improve antijamming capability.
4. the Software for Design of digital displaying meter
The software of PLC system multi-point digital displaying meter mainly shows that by initialization, data receiver and data supervisor forms.
Initialize routine: complete the work such as the initialization of the initialization of I/O mouth, timer, interrupt system of CPU etc. and display buffer, initially demonstration information etc.
Serial data receiving program: receive address information and demonstration data or the radix point that PLC system sends according to the sequential shown in Fig. 2.In the process of image data signal and clock signal level state, adopt reading state and the measure of time delay reading state first mutually, to eliminate the transient noise in state recognition process.The flow process of Serial data receiving program as shown in Figure 4.
(1) first monitoring start signal, is between high period if listen to clock signal, and data-signal has occurred by high level, to low level saltus step, being resolved to start signal.
(2) listen to after start signal, proceed to the 8 bit address information of reception.When the positive transition of each clock signal occurs, the state of image data signal again after time delay 5-10 μ s, is assembled into byte by 8 displacements.
(3) receive after 8 bit address information, proceed to 16 demonstration data or the radix point information of receiving, 16 information of reception resolve to and show data or radix point coding (being the position of radix point) by table 1.
(4) receive 16 and show after data or radix point information, monitor end signal (this is option).Be between high period if listen to clock signal, having there is the saltus step to high level by low level in data-signal, is resolved to end signal.
(5) if the machine address of the address of receiving and setting (arranging by the RC0 and the RC1 that are connected to instrument terminals) difference is lost demonstration data or radix point coding; If identical, will show that charactron segment encode corresponding to data is sent to display buffer, if radix point coding, by the segment encode extreme higher position 1 of this demonstration position, radix point coding continuously effective, until again receive radix point coded message.
Show refurbishing procedure: realized by 5ms Interruption service routine.Often enter 1 interruption, refresh the demonstration information of 1 charactron, guarantee that 4 charactrons can refresh 1 time in 20ms, realize stable demonstration and the demonstration of high-high brightness.Program circuit as shown in Figure 5.
The above; it is only preferably embodiment of the present invention; protection scope of the present invention is not limited to this; any be familiar with those skilled in the art the present invention disclose technical scope in, the simple change of the technical scheme that can obtain apparently or equivalence replace all fall within the scope of protection of the present invention.
Claims (3)
1. the multi-point digital displaying meter driving towards the output of PLC switching value, it is characterized in that, hardware is by power supply, CPU, LED charactron and driving thereof, Serial data receiving the electric circuit constitute, the DC/DC transducer of power supply is LM2596, CPU is PIC16F873, charactron is CA5461, the segment encode of charactron directly uses the I/O mouth of CPU to drive, and by resistance current limliting, the bit code of charactron is used triode 9012 to drive, and Serial data receiving circuit uses MCT6 high speed photo coupling to realize level translation and strengthens interference rejection ability; Software is realized the required sequential of digital displaying meter, data receiver and demonstration.
2. the multi-point digital displaying meter driving towards the output of PLC switching value according to claim 1, is characterized in that, only can realize display data transmissions and the demonstration of PLC system and Duo Tai digital displaying meter with 2 switching value outputs of PLC system.
3. the multi-point digital displaying meter driving towards the output of PLC switching value according to claim 1, it is characterized in that, data transmission sequential between PLC system and digital displaying meter is 24V level, and by transmission beginning, address transfer, display data transmissions, end of transmission (EOT), totally 4 message segment compositions.
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| CN201410230494.2A CN104007694A (en) | 2014-05-28 | 2014-05-28 | Multi-point communication digital indicator for PLC switching value output driving |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104820394A (en) * | 2015-03-17 | 2015-08-05 | 中冶东方工程技术有限公司 | System for driving multivariable instrument by use of PLC digital output module |
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Patent Citations (5)
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| CN2090517U (en) * | 1991-05-08 | 1991-12-11 | 南京钢铁厂 | Multiloop multifunction combination digital indicator |
| WO1997021204A1 (en) * | 1995-12-05 | 1997-06-12 | Schneider Automation | Display device for a programmable controller |
| KR100202706B1 (en) * | 1996-10-05 | 1999-06-15 | 이종수 | Plc remote control system |
| CN201232908Y (en) * | 2008-07-04 | 2009-05-06 | 上海大学 | Integration traffic light and control system thereof |
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| CN104820394A (en) * | 2015-03-17 | 2015-08-05 | 中冶东方工程技术有限公司 | System for driving multivariable instrument by use of PLC digital output module |
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