Network Support For Complex Programmable Logic Device Problems

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Programmable Logic Device family consists of many members like, Field Programmable Device (FPD), Programmable Array Logic (PAL), Field Programmable Gate Array (FPGA), etc. Complex Programmable Logic Device (CPLD) is such logic device. It is more complex than PAL and less complex compared to FPGA. It shares architectural features with both of PAL and FPGA. Macrocell array which consists of flip flops, registers and ALU, is the basic building block of CPLD.

Similarities And Differences With PAL
The structure of CPLD is quite similar to PAL except for the fact that CPLD contains multiple PALs on a single chip. All PALs are interconnected to each other through cross point switches. This similarity makes the CPLD application design much easier for the users who are already familiar with PAL architecture. Like PAL, CPLD does not require external configuration ROM. Because of the similarities, PC support for CPLD could also provided by PAL experts.

Similarities And Differences With FPGA
Like FPGA, CPLD features huge number of logic gates to implement complex data processing functions though the number of logic gates in FPGA is much higher. Both of the devices feature complex feedback paths between macro cells and specialized logic functions. The principal difference between CPLD and FPGA architectures is that CPLD performs logic functions using sum of products equation while FPGA uses look up tables to do the same.

CPLD Architecture
CPLDs are basically integrated circuits that can handle larger designs than PAL but lesser designs than FPGA. A typical CPLD comprises several logic blocks. Each logic block contains 8 to 16 macro cells. Since every logic block performs specific operation, all macro cells in a logic block are interconnected. Logic blocks could be connected to each other depending on the applications. Most of the commonly available CPLDs consist of macro cells, which are designed to perform sum of product combinatorial logic functions, and a non mandatory flip flop. The combinatorial logic functions support 4 to 16 product terms with large number of fan ins based on the CPLD design. The design complexities vary from one CPLD to another depending on the number of logic gates and shift registers used. Due to this reason, FPGA could be replaced with a CPLD equipped with a large number of logic gates. The number of product terms, which a macro cell could manage is an important parameter mentioned in CPLPD specification. Product term is the product of the digital signals that execute a particular logic operation. Since CPLD architecture is quite complex, the design and development should be done with help of network support provider.

CPLD Packages
CPLDs are usually marketed in different IC packages. Different packages have different power consumptions, standby currents, operating currents and supply voltages. Apart from these parameters, CPLDs also vary in terms of memory size and memory support. Memory is usually defined in terms of bits and megabits. Read only memory (ROM), Random Access Memory (RAM) and dual port RAM is included in memory support. Apart from these memories, First In First Out (FIFO) memory, Last In First Out (LIFO) memory and Content Addressable Memory (CAM) are also included in memory support. CPLD memory configuration should be done by an experienced PC support provider.

CPLD Performance Measurement
Performance of CPLD is measured by various parameters, such as internal frequency and propagation delay. Internal frequency indicates the speed at which the CPLD performs logic functions and transfers data within the device. Propagation delay is defined by the time interval between triggering the input signal and the corresponding change in the output signal. Measuring CPLD performance needs technical instruments as well as expertise, which are provided by network support providers.

PC Support For CPLD Problems
Programming and debugging CPLD program require lot of experience, which could be provided by a network support provider. The manufacturers of CPLD, like Xilinx, Atmel, Altera and Cypress render strong PC support for CPLD design and development issues. Apart form the manufacturers, many third party vendors render online round the clock network support for CPLD problems.

Daniel Hughes is one of most heralded content writer of PCCareNCure.com. Pccarencure offers 24x7 PC Support to millions of customers.

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Solutions To Programmable Array Logic Problems Through Network Support

Programmable Logic Array (PAL) is one of the earliest field programmable logic devices, launched in the market in 1978 by Monolithic Memories Inc. It comprises a programmable read only memory core and output circuitry,employed to implement particular digital logic functions. PAL devices are field programmable, which means the device could be programmed by the user. However programming a PAL needs expertise. In case the user faces any problem in PAL programming, an experienced PC support provider should be consulted.

Brief History
In the early days, small scale integration components like transistor transistor logic (TTL) were used to build a digital circuit. Among the TTL families, 7400 series was very popular. It consisted of variety of logic gates, multiplexers,demultiplexers,flip flops,etc. After the advent of PAL, SSI devices became obsolete.

PAL Technology
Early versions of PAL were 20 pin dual inline package. Bipolar transistor technology was used to fabricate PAL. Titanium tungsten programming fuses were used in those one time programmable devices. Later on,Advanced Micro Devices employed CMOS technology to manufacture PALs for which it provided extensive network support.

Architecture Of PAL
The programmable elements in a PAL link the true and complemented inputs to the AND gates. These AND gates are also called Product Terms. Product Terms are ORed altogether to constitute a sum of products logic array. The PAL architecture comprises two principal components, namely Programmable Logic Plane and Output Logic Cells.

Programmable Logic Plane
Programmable Logic Plane is nothing but a programmable read only memory which routes the signals at the input pins to the output logic macro cells. PAL devices feature transistor cell arrays which are organized in a fixed OR programmable AND fashion. Sum of products logic equations for each output in terms inputs and feedback from output are implemented by these arrays.

Output Logic Macro Cells
A standard 20 pin PAL features 8 outputs,10 inputs, 1 pin for power and 1 pin for ground. In the active state the signal at the output pins is 0 volt. The output could be either combinational or registered. A standard PAL device features different output structures, known as Output Logic Macro Cells or OLMC. Earlier versions of PAL, such as 16L8 and 16R8 had fixed OLMCs at the time of manufacturing. Later, in 1983, AMD launched 22V8, whose OLMCs could be configured by the user as registered or combinational.

PAL Programming
PAL programs are written using Hardware Description Languages, such as ABEL,CUPL and PALSM. These are computer aided design programs, which convert the PAL logic equations written in a text file to binary files, like JDEC and HEX files. These binary files are programmed into PAL devices using special programming devices. The manufacturers as well as the third party manufacturers render strong PC support for PAL programming issues.

PALASM Language
PALSM language was invented to write boolean logic equations for the configured output pins using the configured input pins. The equations are written in a text file,which is then converted into a binary file using compiler. Monolithic Memories Incorporation (MMI) wrote first compiler for PALASM language in FORTRAN IV on IBM 370/168. MMI supplied the free compiler and network support to the PALASM users.

ABEL Language
Advanced Boolean Expression Language (ABEL) is a hardware description language developed by Data I/O Corporation in 1983 for programming PALs. It employs concurrent equations,truth table logic format and sequential state machine diagram. Data I/O Corporation provides compiler as well as PC support for ABEL language.

CUPL Language
CUPL language was invented by Logical Devices Incorporation. Its earlier versions ran under MS DOS. Now it comes as an integrated development package of windows. CUPL programming issues could be resolved with the network support of Logic Devices Inc.

PC Support For PAL Programming
PAL programing requires experience in handling compiler as well as PAL programming devices which could be made easier with the help of network support providers. PAL manufacturers provide extensive PC support for PAL programming. Apart from that, a lot of third party vendors render strong network support for PAL programming issues.

Daniel Hughes is one of most heralded content writer of PCCareNCure.com. Pccarencure offers 24x7 PC Support to millions of customers.

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Network Support For Programmable Logic Controller Problems

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Nowadays Programmable Logic Controllers or PLCs are widely used in a lot of industries. These devices are basically industrial digital computers which are employed to monitor the inputs to the process and control the outputs based on the state of inputs. The primary objective of PLC is to automate machines or industrial processes like machinery control on a factory assembly lines, relay control, motion control, process control, distributed control, etc. There are numerous manufacturers in the market today, such as Alstom, ABB, Hitachi, Motorola, Panasonic, Siemens, Mitshubishi, etc, which not only produce state of the art PLCs but also provide excellent PC support to their products.

Definition
As per the definition by National Electrical Manufacturing Association, a PLC is defined as "A digitally operating electronic apparatus which uses a programmable memory for the internal storage of instructions by implementing specific functions such as logic sequencing, timing, counting, and arithmetic to control, through digital or analog input/output modules, various types of machines or processes".

Brief History
Initially PLC was invented to meet the growing needs of the automotive manufacturing industry. Before advent of PLC, the complex industrial process was controlled by plenty of relays, dedicated closed loop controllers, drum sequencers and cam timers. The task of updating such huge control system was very cumbersome and costly. To overcome these shortcomings, digital computer was employed to regulate the industrial control process. GM Hydramatic, the automatic transmission division of General Motors, was the first company to call for a tender to replace its hard wired relay system in 1968. Bedford Associates won the bid and produced the first PLC in the market. It was named 084, since it was the 84th project of Bedford Associates. Since then thousands of PLCs have been launched in the market. All the manufacturers of PLCs provide extensive network support to their clients.

Development
The objective of the earlier version of PLCs was to replace the relay logic systems. A programming language called Ladder Logic was used to program those devices. Ladder Logic described the function by a graphical drawing of the circuit diagrams of the relay logic hardware. Later, many other traditional programming languages like Basic, C, etc. were developed to program the PLCs. Apart from traditional programming languages, state transition diagram based languages like State Logic is also used widely. Branded programming terminals were used to program the earlier versions of PLCs till the mid 1980s. Nowadays application software on PCs can directly program the PLCs through RS232, RS422, RS485, Ethernet ports. Assistance of a PC support provider could be taken to diagnose any problem in communicating with the PLCs through ports.

Applications
PLC is the main component of any process control system. Multiple PLCs could be connected to the main PC to control complex processes like motion control, distributed control system, networking, process control, sequential relay control, etc. In terms of communication, storage, data handling and processing capabilities, some of the latest PLCs could compete against a la mode PCs. Because of the extensive input/output design, PLCs could be connected to sensors and actuators without much hassle. Through sensors, PLCs could monitor process variables like pressure, temperature, switches position, etc. Magnetic relays, solenoids, pneumatic cylinders, electric motors could be controlled by the PLCs through actuators. For debugging the sensor and actuator problems, extensive network support is provided by the manufacturers of PLCs.

PC Support For PLC Problems
Designing, developing and debugging a complex process control system using PLC is quite an arduous task, which could be made easier with the network support of PLC manufacturers. At present many third party vendors also provide extensive PC support for any type of PLC system problems.

Daniel Hughes is one of most heralded content writer of PCCareNCure.com. Pccarencure offers 24x7 PC Support to millions of customers.

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