conversations.from: human
conversations.value: What could be a title for a story about PLCs, PLC, Computing with the genre: Engineering & Transportation, Engineering?
conversations.from: assistant
conversations.value: A title for this story could be 'Programmable Logic Controllers'
conversations.from: human
conversations.value: Give me a description for a story titled Programmable Logic Controllers about PLC, PLCs, Simatic with the genre: Engineering & Transportation, Engineering.
conversations.from: assistant
conversations.value: An easy-to-read alternative to the expensive and jargon-filled manual sets, this reference describes how to set up and troubleshoot a PLC in general, and covers implementation in specific leading proprietary PLC systems: Allen-Bradley (PLC-5 and SLC 500), Siemens (Simatic S5 and Simatic S7), and OMRON (all, but specifically CQM1). It includes, but goes beyond, simple Boolean logic enabling readers to use all of the power of a modern PLC. Complete coverage of capabilities of modern PLCs; extensive troubleshooting coverage; full instructions (for Boolean logic, timing and counting, data manipulation, process control, and communication) -- with at least one instruction of each type described in detail and similar instructions described in terms of what they do differently; setup and configuration requirements of all PLCs. For anyone interested in programming and configuration of Programmable Logic Controllers (PLCs) for industrial control.
conversations.from: human
conversations.value: Give me the first three paragraphs for this story.
conversations.from: assistant
conversations.value: Programmable Logic Controllers
  As an illustration of the use of these terms in specification, the following were included in the specification of a MX100AP pressure sensor (see later in this chapter, Section 2.1.8, for an explanation of this sensor):
  A mechanical switch generates an on/off signal or signals as a result of some mechanical input causing the switch to open or close. Such a switch might be used to indicate the presence of a workpiece on a machining table, the workpiece pressing against the switch and so closing it. The absence of the workpiece is indicated by the switch being open and its presence by it being closed. Thus, with the arrangement shown in Figure 2.3a, the input signals to a single input channel of the PLC are thus the logic levels:
  With the arrangement shown in Figure 2.3b, when the switch is open the supply voltage is applied to the PLC input; when the switch is closed the input voltage drops to a low value. The logic levels are thus:
conversations.from: human
conversations.value: Give me five more paragraphs.
conversations.from: assistant
conversations.value: Figure 6.5a shows Mitsubishi notation. With such a situation, Mitsubishi uses an ORB instruction to indicate "OR together parallel branches." The first instruction is for a normally open pair of contacts X400. The next instruction is for a series set of normally closed contacts X401, hence ANI X401. After reading the first two instructions, the third instruction starts a new line. It is recognized as a new line because it starts with LDI, all new lines starting with LD or LDI. But the first line has not been ended by an output. The PLC thus recognizes that a parallel line is involved for the second line and reads together the listed elements until the ORB instruction is reached. The mnemonic ORB (OR branches/blocks together) indicates to the PLC that it should OR the results of the first and second instructions with that of the new branch with the third and fourth instructions. The list concludes with the output OUT Y430. The instruction list would thus be entered as:
  Figure 6.5b shows the Siemens version of an XOR gate. Brackets are used to indicate that certain instructions are to be carried out as a block. They are used in the same way as brackets in any mathematical equation. For example, (2 + 3) / 4 means that the 2 and 3 must be added before dividing by 4. Thus with the Siemens instruction list we have in step 0 the instruction A(. The brackets close in step 3. This means that the A in step 0 is applied only after the instructions in steps 1 and 2 have been applied.
  The IEC 61131-3 standard for such programming is to use brackets in the way used in the previous Siemens example, that is, in the same way brackets are used in normal arithmetic. This enables instructions contained within brackets to be deferred until the bracket is completed. Thus the IEC instruction list program:
  Figure 6.6 shows a circuit that can be considered as two branched AND blocks. Figure 6.6a shows the circuit in Mitsubishi notation. The instruction used here is ANB. The instruction list is thus:
  Figure 6.6b shows the same circuit in Siemens notation. Such a program is written as an instruction list using brackets. The A instruction in step 0 applies to the result of steps 1 and 2. The A instruction in step 4 applies to the result of steps 5 and 6. The program instruction list is thus:
conversations.from: human
conversations.value: Delete the first sentence.
conversations.from: assistant
conversations.value: 5a shows Mitsubishi notation. With such a situation, Mitsubishi uses an ORB instruction to indicate "OR together parallel branches." The first instruction is for a normally open pair of contacts X400. The next instruction is for a series set of normally closed contacts X401, hence ANI X401. After reading the first two instructions, the third instruction starts a new line. It is recognized as a new line because it starts with LDI, all new lines starting with LD or LDI. But the first line has not been ended by an output. The PLC thus recognizes that a parallel line is involved for the second line and reads together the listed elements until the ORB instruction is reached. The mnemonic ORB (OR branches/blocks together) indicates to the PLC that it should OR the results of the first and second instructions with that of the new branch with the third and fourth instructions. The list concludes with the output OUT Y430. The instruction list would thus be entered as:
  Figure 6.5b shows the Siemens version of an XOR gate. Brackets are used to indicate that certain instructions are to be carried out as a block. They are used in the same way as brackets in any mathematical equation. For example, (2 + 3) / 4 means that the 2 and 3 must be added before dividing by 4. Thus with the Siemens instruction list we have in step 0 the instruction A(. The brackets close in step 3. This means that the A in step 0 is applied only after the instructions in steps 1 and 2 have been applied.
  The IEC 61131-3 standard for such programming is to use brackets in the way used in the previous Siemens example, that is, in the same way brackets are used in normal arithmetic. This enables instructions contained within brackets to be deferred until the bracket is completed. Thus the IEC instruction list program:
  Figure 6.6 shows a circuit that can be considered as two branched AND blocks. Figure 6.6a shows the circuit in Mitsubishi notation. The instruction used here is ANB. The instruction list is thus:
  Figure 6.6b shows the same circuit in Siemens notation. Such a program is written as an instruction list using brackets. The A instruction in step 0 applies to the result of steps 1 and 2. The A instruction in step 4 applies to the result of steps 5 and 6. The program instruction list is thus:
conversations.from: human
conversations.value: Give me the last two paragraphs.
conversations.from: assistant
conversations.value: The WHILE... DO iteration statement allows one or more statements to be executed while a particular Boolean expression remains true.
  The REPEAT... UNTIL iteration statement allows one or more statements to be executed and repeated while a particular Boolean expression remains true.