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Introduction of PLC Enclosures
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Date:2010-04-24 20:47:13Click:54Comment:0
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| PLCs are well built and rugged, but they are still relatively easy to damage on the factory floor. As a result, enclosures are often used to protect them from the local environment. Some of the most important factors are listed below with short expl |
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Security problem of Internet
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Date:2009-12-23 05:58:15Click:17Comment:0
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| Security problems usually arise through protocols. For example it is common for a hacker to gain access through the mail system. The system administrator is responsible for security, and if you are using the campus server, security problems will nor |
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Data Highway and it's application in Allen-Bradley plc5
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Date:2009-10-22 05:57:56Click:73Comment:0
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| Allen-Bradley has developed the Data Highway II (DH+) network for passing data and programs between PLCs and to computers. This bus network allows up to 64 PLCs to be connected with a single twisted pair in a shielded cable. Token passing is used to |
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Communicating with Devicenet Inputs and Outputs
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Date:2009-08-06 08:57:10Click:54Comment:0
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| Some of the design issues for this network include; Power supplies are directly connected to the network power lines. Length to speed is 156m/78m/39m to 125Kbps/250Kbps/500Kbps respectively. A single drop is limited to 6m. Each node on the network w |
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Introduction for String Manipulation Functions
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Date:2009-05-06 06:31:24Click:69Comment:0
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| Many of the remaining string functions are illustrated in See String Manipulation Functions. When A is true the ABL and ACB functions will check for characters that have arrived on channel 1, but have not been retrieved with an ARD function. If the |
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A String to Integer Conversion Example with ladder logic
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Date:2009-05-06 06:30:01Click:74Comment:0
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| The ASCII functions can also be used to support simple number conversions. The example in See A String to Integer Conversion Example will convert the strings in ST9:10 and ST9:11 to integers, add the numbers, and store the result as a string in ST9: |
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An ASCII String Example in PLC system
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Date:2009-05-06 06:29:09Click:151Comment:0
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| In the example in See An ASCII String Example, the characters Hi are placed into string memory ST10:1. A zero is used to indicate the end of the string. The ACB function checks to see how many characters have been received, and are waiting in channe |
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Introduction of PLC-5 ASCII Functions
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Date:2009-05-06 06:28:31Click:59Comment:0
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| ASCII functions allow programs to manipulate strings in the memory of the PLC. The basic functions are listed in See PLC-5 ASCII Functions. PLC-5 ASCII Functions |
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ABB PLC software
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Date:2008-11-07 07:06:18Click:226Comment:0
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| ABB Automation Tech has developed crane control software that brings increased safety, reliability and performance to industrial, harbour and tower cranes, for use with its variable- speed drives. Called Crane Control Program, the software is an opt |
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Configuration Data for a 1771-OFE Output Card
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Date:2008-10-18 19:53:40Click:162Comment:0
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| The configuration memory structure for the 1771-OFE Analog Output Card is shown in See Configuration Data for a 1771-OFE Output Card. The card has four 12 bit output channels. The first four words set the output values for the card. Word 0 (N9:0) se |
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The PLC-5 ladder logic in Controlling a 1771-OFE Analog Output Card
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Date:2008-10-18 19:52:30Click:136Comment:0
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| The PLC-5 ladder logic in See Controlling a 1771-OFE Analog Output Card can be used to set analog output voltages with a 1771-OFE Analog Output Card. The BTW instruction will write configuration memory to the card (the contents are described later). |
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Data Returned by the 1771-IFE Analog Input Card
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Date:2008-10-18 19:49:38Click:43Comment:0
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| The block of data returned by the BTR statement is shown in See Data Returned by the 1771-IFE Analog Input Card. Bits 0-2 in word 0 (N7:10) will indicate the status of the card, such as error conditions. Words 1 to 4 will reflect status values for e |
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Configuration Data for an 1771-IFE Analog Input Card
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Date:2008-10-18 19:48:51Click:86Comment:0
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| The data to configure a 1771-IFE Analog Input Card is shown in See Configuration Data for an 1771-IFE Analog Input Card. (Note: each type of card will be different, and you need to refer to the manuals for this information.) The 1771-IFE is a 12 bit |
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Ladder Logic to Control an Analog Input Card
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Date:2008-10-18 19:48:19Click:178Comment:0
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| The PLC 5 ladder logic in See Ladder Logic to Control an Analog Input Card will control an analog input card. The Block Transfer Write (BTW) statement will send configuration data from integer memory to the analog card in rack 0, slot 0. The data fr |
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Structured Text Functions of the IEC1131-3 defined functions
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Date:2008-09-28 06:44:51Click:43Comment:0
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| The list below gives a most of the IEC1131-3 defined functions with arguments. Some of the functions can be overloaded (for example ADD could have more than two values to add), and others have optional arguments. In most cases the optional arguments |
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