JPH07182013A - Method and apparatus for discrimination of input/output module coupled to programmable logic controller - Google Patents

Abstract

PURPOSE: To communicate the type of a module with which a controller communicates by providing a module ID bus for easily identifying the type of the module connected with a main bus. CONSTITUTION: A specific I/O module is enabled by activating an SOLT ENABLE line corresponding to the I/O module. Next, data are transmitted to the I/O module, and the data are transferred from the enabled I/O module 105 to the other parts of a controller 50. The I/O module 105 transmits the unique module ID code to a module ID bus 90 simultaneously with the transmission of the data. This module ID code is received by an I/O control master(IOCM) 95. Then, a CPU 54 decides which type of I/O module is enabled, and made correspond to the I/O module.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates generally to programmable logic controllers or writable logic controllers, and more particularly to a method and method for identifying an input / output module coupled to a programmable logic controller. It relates to the device.

[0002]

2. Description of the Related Art Programmable logic controllers (PLCs) or writable logic controllers are a relatively recent development in process control technology. As part of the process control, the programmable logic controller
It is used to monitor input signals from various input points (input sensors) that report events and conditions that occur in the controlled process. For example, PL
C can monitor input conditions such as motor speed, temperature, pressure and volume flow rate. A control program is stored in memory within the PLC to instruct the PLC what action to take when a particular input signal or condition is encountered. In response to these input signals provided by the input sensor, the PLC derives and produces an output signal which is transmitted via the PLC output point to various output devices to control the process. To do. For example, the PLC produces output signals to raise or lower conveyor speed, rotate robot arms, open or close relays, raise or lower temperature, and many other possible control functions.

The input and output points described above are typically
Each is associated with an input board and an output board. Those skilled in the art will combine such input and output boards into I / O.
It is called (input / output) board. I / O like this
Boards are also called I / O cards or I / O modules. These I / O modules can be plugged into their respective slots located on the backplane board in the PLC. The slots are integrally coupled by a main bus, and the main bus is any I / O plugged into the slot.
Bind the module to the processor.

Many different types of I / O modules can be inserted into the multiple slots typically found in PLCs. For example, 8 or 1
It is possible to couple 6 point input modules, 8 or 16 point output modules, high speed counters and many other types of I / O modules to the PLC.

It is desirable for a processor in a PLC to be able to easily identify the type of I / O module with which it is communicating. Traditionally, the process of communicating with an I / O module involves separate and discrete sequential steps that identify a particular module and initiate the transfer of data to or from that module. It was Performing such steps requires multiple clock cycles to perform.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to reduce the amount of time required by a PLC to identify a particular I / O module and communicate with it. It is to provide a method of operating a PLC. Another object of the present invention is to provide a method of operating a PLC that reduces the hardware required at the interface between the input module and the PLC. Yet another object of the present invention is to provide a PLC operating method in which the configuration of the output module is simplified.

[0007]

According to the present invention, there is provided a method of operating a programmable logic controller (writable logic controller). A controller embodying the invention has a central processor coupled to the main bus. The main bus is capable of coupling to input / output modules and has a serial input / output bus for data communication and a module ID bus that facilitates identification of the type of module coupled to the main bus. ing.
The method of the invention comprises the step of enabling the module. The method further comprises transferring data between the controller and the enabled module via a serial input / output bus. The method further comprises the step of providing module ID information in which the enabled module represents the type of module enabled. The module ID information is provided by the enabled module at the same time as the data is transferred by the enabled module in the data transfer step.
Supplied to the bus. Thus, the controller is informed of the type of module with which it is communicating.

Further in accordance with the present invention, a programmable logic controller device is provided, the controller device having a central processor. The controller further has a main bus with a serial input / output bus for communicating serial data and a module ID bus for receiving module ID information. The controller is
Further, at least one input / coupled to the main bus
It has an output module and an enable circuit for selectively enabling a particular input / output module when more than one input / output module is coupled to the main bus. The input / output module has data transfer circuitry for transferring data between the module and the serial input / output bus when the module is enabled. The input / output module further transmits module ID information on the module ID bus at substantially the same time that data is transferred between the module and the serial input / output bus. It has a module ID transmission circuit for. In this way, the controller is informed of the type of module with which it is communicating.

[0009]

1 is a block diagram of a programmable logic controller (writable logic controller) device 10 constructed in accordance with one embodiment of the present invention and capable of carrying out the method of the present invention.
It is a schematic block diagram showing. The controller 10
It has a central processor 15, which may be, for example, a microprocessor, which is coupled via a main bus 25 to a plurality of module receiving slots 20. The main bus 25 has an address and data bus portion. The processor 15 is coupled to a read only memory (ROM) 30 in which the memory
Software for controlling the operation of controller 20 is permanently stored. Processor 15 is further coupled to random access memory (RAM) 35, which provides controller 10 with a temporary storage location. In one embodiment of the invention, the central processor 15, slot 20, bus 25, ROM 30, RA
All of the M35s are manufactured on a common backplane 40 or motherboard. Meanwhile, the slot 20 and the bus 25
Manufactured on a common backplane, while the processor 1
5, ROM 30, RAM 35, and associated support circuits are located on the plug-in card or module, which module may be referred to as the central processing unit module or CPU module. Slot 20 receives therein respective input / output (I / O) modules (not shown).

It should be understood that when the term I / O module is used, it refers to an input module, an output module or a module that has both input and output capabilities. . It should be further understood that the input module has a plurality of input points (not shown) where the data from the controlled process is provided. It should be further understood that the output module has a plurality of output points (not shown) where control information is delivered to the controlled process.

FIG. 2 illustrates the programmable logic controller device of the present invention (shown as controller 50).
3 is a schematic block diagram showing a more detailed configuration of FIG. The controller 50 accepts a CPU module 52 therein instead of having a central processor integrated on the backplane board. The controller 50 has a backplane board 55, and the backplane board 55 has module receiving slots 60, 65, 70.
The slots are all connected in parallel by the main bus 75. The main bus 75 is
It has a serial data and clock and parallel board identification (ID) bus 90, which in this embodiment is bus 9.
0 is 5 board ID lines BID0, BID1, BI
It has D2, BID3 and BID4. The operation of the board ID bus 90 will be described in more detail below.

Input / Output Control Master (IOCM) Circuit 9
5 is also located in the CPU module 52 in this embodiment of the invention. The IOCM 95 controls collection and distribution of data on the serial I / O bus described later. More specifically, the IOCM circuit 95 is
It controls the O communication and communicates with the CPU 54. IO
The CM circuit 95 also inputs / outputs on the corresponding I / O module 105 inserted in the slots 60, 65, 70.
It communicates with the output control slave circuit (ICS or OCS) 100. The IOCS circuit 100 on the I / O module 105 interfaces such a module with the main bus 75, as described in more detail below. The controller 50 may also have additional slots coupled to the main bus 75 to receive other I / O modules 105.

The IOCM 95 is a board ID input 95.
(0), 95 (1), 95 (2), 95 (3), 95
(4), which are respectively board ID lines BID0, BID1, BID of the board ID bus 90.
2, BID3, BID4. IOCM9
5 has a respective slot enable output for each of the slots 60, 65, 70. That is, IOCM
As shown in FIG. 2, 95 is a SLOT ENABLE1 output terminal connected to the slot 60 and a SLOT ENABLE2 output terminal connected to the slot 65 via the slot enable line 110 in the main bus 75.
A SLOT ENABLE3 output coupled to slot 70. When the IOCM drives one of the slot enable lines to the true state, the I / O modules located in each of the slots coupled to it will respond to either input or output of data. Enabled In order to facilitate this enable operation, each of the modules 105 has a MODULE
It has an ENABLE (module enable) input, which is SLOT ENAB when the module is inserted into a slot on the main bus 75.
LE LINE (slot enable line) 1, 2,
Associated with each one of the three. For example, slot 6
MODUL of the specific module 105 to be inserted into
The E ENABLE input is the S associated with slot 65.
MODU of specific module 105 coupled to LOT ENABLE line and inserted in slot 70
The LE ENABLE input is coupled to the SLOT ENABLE 3 line associated with slot 70.

It should be noted that IOCM95
Performs serial communication with the ICS and OCS on the I / O module 105. More specifically, IOCM
95 has a serial I / O data output, which is coupled to serial I / O data line 115 in bus 75. I / O module 105 has slots 65 and 7
When inserted into 0, the serial output (not shown) in module 105 is coupled to serial I / O data line 115 so module 105 can communicate serially with the data on serial I / O bus 115. Is possible.

The pinout arrangement of the main bus 75 is shown in Table 1 below. It should be noted that the main bus 75 has several lines not shown in FIG. 2 but shown in Table 1 for completeness.

Table 1 LGND logic ground + 5VDC logic power SDATA serial data SCLK serial clock 1MHz driven by CPU BDSEL board (module) select RD / WT read / write BID0-BID4 board ID R24 relay power RNDND relay return + 24VDC isolated 24V IGN isolated Return * RST Reset FGND Frame / shield ground Slot enable 1,2,3 Slot enable bus 110 The LGND line (not shown) of the main bus 75 provides logical ground. + 5VDC line (not shown) is slot 6
Supplies logical power to I / O modules plugged into 0-70. The SDATA line corresponds to the serial I / O data line 115 of the main bus 75. The SCLK line is a serial clock line,
It corresponds to the CLOCK line of the main bus 75. The 1 MHz line is the clock line and provides a 1 MHz time base frequency driven by the CPU module 52. The BDSEL line is a board or module select line. The RD / WRITE line is a read / write line and its logic state is changed according to whether the module receives data or sends data. Board ID line BID0, BID
1, BID2, BID3, BID4 carry the digital code generated by each I / O module 105 according to its type. Different types of I / O modules generate different unique logic codes to identify them, as will be described in more detail below.

The R24 line and the RGND line are the relay power and relay ground lines used respectively by the type of module referred to as the relay output module, and drive the relay coil couplable to it. The + 24V DC line and the IGND line provide isolated power to each module inserted in the backplane slot and are used as input points by such modules. * RST line provides system reset. The FGND line provides frame / shield ground to controller 50.
The slot enable line 110 has already been described.

In this particular embodiment of the invention, I
Each of the / O modules 105 is capable of generating a 5-bit code (Module ID Code) that identifies the particular type of module. More specifically, the IOCS 100 located on each module 105.
Generates this module ID code, and when the module is enabled by an enable signal on any one of the slot enable lines 110, such a module 105 will send its unique module ID code to the module ID bus line. Supply to BID0-BID4. As an example, each module ID code and corresponding module type is shown in Table 2 below.

Table 2 Module ID code (BID0-BID4) Module type 11110 8-point output 11101 8-point input 11011 16-point output 10111 16-point input 01110 32-point output 01111 32-point input 01101 High-speed counter 01011 Analog output 00111 Analog input 10101 Intelligent Module 11111 Module Not Present 0000 Expansion Rack Unknown As those skilled in the art will appreciate, it is also possible to use module ID codes with different bit widths, i. For example, if only two different types of modules are used in the controller 50, it is possible to use a single bit as the bit width of the module ID code. However, in general, the bit width of the module ID code is
It uses multiple bits to provide identification of a number of different types of modules.

IOCM 95 when an input / output control master (IOCM) 95 accesses a particular one of I / O modules 105 for input or output.
First enables that particular module by activating a single slot enable line. For example, the IOCM 95 is the I / O in the slot 65.
When accessing the module 105, IOCM9
5 activates the SLOT ENABLE 2 line,
Depending on the capabilities of that module, it enables the module 105 for input or output. Slot 65
Since a particular I / O module within is accessed or enabled, it is referred to as an enabled I / O module 105 to distinguish it from other non-enabled I / O modules 105. The enabled I / O module 105 has its MODULE
Upon determining that the ENABLE line goes to the true state, the module 105 either sends the data it collects through the serial I / O bus 115 or the serial I / O bus 115.
Data is received via the / O data bus 115. If the enabled I / O module 105 has its SLOT E
At substantially the same time as observing the NABLE signal and transmitting or receiving its data, the enabled I /
O-module 105 asserts its module ID code on module ID bus 90.

Referring to 2 of the interim table, if the enabled I / O module 105 is an 8-point output module, the module 105 will send the module ID bus 90.
Assert the module ID code 11110 above.
It should be noted that the transmission of the module ID code by module 105 on module ID bus 90 occurs at about the same time module 105 transmits or receives data on serial I / O bus 115. Be done. In other words, in this way,
The module 105 transmits its module ID code at substantially the same time as the module 105 transmits or receives data via the serial bus 115. S
When the LOT ENABLE signal ends (goes to a false state), IOCM 95 latches the module ID code found on module ID bus 90. In this manner, the controller 50 will know the type of I / O module with which it was communicating. The controller 50 also checks the particular modules 105 to determine how many input or output points are assigned to such modules.

In the above described embodiment of the invention, the module ID data is sent at the same time as it is sent to or received from the module 105, so that an additional clock cycle for the transmission of the module ID. Is never needed. Significant architectural efficiency in the controller 50 and its associated input / output module hardware is achieved in this manner.

A flow chart showing the operation of the method of the present invention is shown in FIG. The method is summarized by the following steps. First, as shown in block 200,
A specific I / O module has a corresponding SLOT ENABLE (slot enable)
It is enabled by activating the line. The data is then transferred to the controller 5 such as from the CPU module 52 or from the IOCM module 95, etc.
Transferred from the other part of 0 to the enabled I / O module. On the other hand, the data is now transferred from the enabled I / O module 105 to the rest of the controller 50. This data transmission activity is indicated by block 205 in the flow chart of FIG. The particular enabled I / O module 105 at substantially the same time that data is sent to or from the I / O module as indicated by block 205.
Sends its unique module ID code on the module ID bus 90, as shown in block 210.
This unique module ID code is received by the I / O control master (IOCM) 95 which latches the module ID code as shown in block 215. CPU5
4 reads the module ID code in the IOCM 95 and uses that code to associate with the CPU 54 the EPR
Access a look-up table stored in the OM to determine which type of I / O module is enabled and corresponds to the I / O module. Thus, the controller 50 is informed about the particular type of I / O module with which it is communicating, at which time
It does not require another access at another time from the actual data transfer to determine such information.

The programmable logic controller and its control operation have been described in detail based on the embodiments.
The present invention significantly reduces the amount of time required by the controller to identify and communicate with a particular I / O module.

Although specific embodiments of the present invention have been described in detail above, the present invention should not be limited to these specific examples, and various modifications can be made without departing from the technical scope of the present invention. It goes without saying that the above can be modified.

[Brief description of drawings]

FIG. 1 is a schematic block diagram showing a programmable logic controller device configured according to an embodiment of the present invention.

FIG. 2 is a schematic block diagram showing a more detailed configuration of the programmable logic controller device of the present invention.

FIG. 3 is a flow chart diagram illustrating steps in a method of communicating data in a programmable logic controller according to one embodiment of the invention.

[Explanation of symbols]

 10 Programmable Logic Controller Device 15 Central Processor 20 Module Reception Slot 25 Main Bus 30 ROM 35 RAM 40 Backplane 50 Programmable Logic Controller 52 CPU Module 55 Backplane Board 60, 65, 70 Slot 75 Main Bus 95 Input / Output Control Master (IOCM) ) Circuit 100 IOCS circuit 105 I / O module

 ─────────────────────────────────────────────────── ———————————————————————————————————————————————————————————————————————————————————−−−−−−−−−––––––––––––––––––––––––––––––––––––– 2900

Claims (12)

[Claims] 1. A method of operating a programmable logic controller, wherein said controller has a central processor coupled to a main bus, said main bus being capable of being coupled to an input / output module, said main bus further comprising a data processor. A serial input / output bus for communication and a module ID bus for facilitating identification of the type of module coupled to the main bus; the method enables the module and the serial input / Transferring data between the controller and the module via an output bus and providing module ID information representative of the type of the module by the module, the module ID information being The data is transferred in the data transfer step Substantially simultaneously with the module I
A method characterized in that the controller is informed of the type of module that is fed to the D-bus and with which the controller communicates. 2. The module I according to claim 1, further comprising latching said module ID information and thus latching it.
A method comprising: making D information. 3. The module I according to claim 2, further comprising:
Accessing a look-up table having D code information and corresponding module type information, and correlating the latched module ID information with the corresponding module ID code information in the look-up table to determine the type of the module. A method comprising the steps of: 4. In a programmable logic controller, a central processor is provided and a main bus is provided that includes a serial input / output bus for communicating serial data and a module ID bus for receiving module ID information. At least one input / output module coupled to the main bus, and enabling means for selectively enabling the at least one input / output module, the at least one input / output module being provided. Data transfer means for transferring data between the module and the serial input / output bus when the module is enabled; and the data having the module and the serial input / output bus. The type of module at substantially the same time that it is transferred between And a module ID transmitting means for transmitting module ID information indicating the module ID to the module ID bus, and the controller is notified of the type of module with which the controller communicates. 5. The device according to claim 4, further comprising latch means for latching the module ID information,
Therefore, the programmable logic controller characterized in that the latched module ID information is obtained. 6. The module I according to claim 5, further comprising:
A programmable logic controller having a look-up table containing D information and corresponding module type information. 7. The method of claim 6, further comprising the latched module ID information corresponding module type information in the look-up table to determine the type of input / output module enabled by the enabling means. A programmable logic controller, characterized in that it is provided with correlating means for correlating with. 8. The module ID according to claim 4.
A programmable logic controller characterized in that the bus has a parallel bus. 9. In a programmable logic controller, a central processor is provided, a backplane board is provided, a plurality of slots are located on the backplane board, and the plurality of slots are respectively provided. Any input / output module positioned within the slot, wherein the at least one input / output module is located in one of the slots Input / output control means are located on the backplane board to control input / output operations of the mainframe, and a main bus is located on the backplane board to integrally couple the slots. , The central processor and the input / output control means are coupled to the main bus, The main bus includes a serial input / output bus for data communication and a module ID bus for receiving module ID information from the input / output module, and includes an input / output module located in the slot. An enabling means is provided for transmitting an enable signal to a selected one of the slots for enabling, each input / output module located in the slot being provided with an enable signal when the module is enabled. Data transfer means for transferring data between the module and the serial input / output bus; and at the same time when the data is transferred between the module and the serial input / output bus. The module ID information indicating the type is stored in the module I
A latch means for latching the module ID information to obtain module ID information processed by the input / output control means and latched as a result. The programmable logic controller is characterized in that the type of module with which the input / output control means communicates is notified to the input / output control means. 10. The programmable logic controller according to claim 9, further comprising a lookup table containing module ID information and corresponding module type information. 11. The method of claim 10, further comprising the latched module ID information corresponding module type information in the look-up table to determine the type of input / output module enabled by the enabling means. A programmable logic controller, characterized in that it is provided with correlating means for correlating with. 12. The module I according to claim 9,
A programmable logic controller, wherein the D bus has a parallel bus.