Post by Ed Bingle on May 13, 2014 8:17:48 GMT -5
Machine Controls.
Machine control
Machine-to-Machine
Machine-to-machine (M2M) refers to technologies that allow both wireless and wired systems to communicate with other devices of the same ability. M2M uses a device (such as a sensor or meter) to capture an event (such as temperature, inventory level, etc.), which is relayed through a network (wireless, wired or hybrid) to an application (software program), that translates the captured event into meaningful information (for example, items need to be restocked). Such communication was originally accomplished by having a remote network of machines relay information back to a central hub for analysis, which would then be rerouted into a system like a personal computer.
However, modern M2M communication has expanded beyond a one-to-one connection and changed into a system of networks that transmits data to personal appliances. The expansion of wireless networks across the world has made it far easier for M2M communication to take place and has lessened the amount of power and time necessary for information to be communicated between machines. These networks also allow an array of new business opportunities and connections between consumers and producers in terms of the products being sold.
Relay logic
Relay logic is a method of controlling industrial electronic circuits by using relays and contacts.
Ladder logic
Main article: ladder logic
The schematic diagrams for relay logic circuits are often called line diagrams, because the inputs and outputs are essentially drawn in a series of lines. A relay logic circuit is an electrical network consisting of lines, or rungs, in which each line or rung must have continuity to enable the output device. A typical circuit consists of a number of rungs, with each rung controlling an output. This output is controlled by a combination of input or output conditions, such as input switches and control relays. The conditions that represent the inputs are connected in series, parallel, or series-parallel to obtain the logic required to drive the output. The relay logic circuit forms an electrical schematic diagram for the control of input and output devices. Relay logic diagrams represent the physical interconnection of devices. The basic format for relay logic diagrams is as follows:
1. The two vertical lines that connect all devices on the relay logic diagram are labeled L1 and L2. The space between L1 and L2 represents the voltage of the control circuit.
2. Output devices are always connected to L2. Any electrical overloads that are to be included must be shown between the output device and L2; otherwise, the output device must be the last component before L2.
3. Control devices are always shown between L1 and the output device. Control devices may be
connected either in series or in parallel with each other.
4. Devices which perform a STOP function are usually connected in series, while devices that
perform a START function are connected in parallel.
5. Electrical devices are shown in their normal conditions. An NC contact would be shown as
normally closed, and an NO contact would appear as a normally open device. All contacts
associated with a device will change state when the device is energized.
Figure 1 shows a typical relay logic diagram. In this circuit, a STOP/START station is used to
control two pilot lights. When the START button is pressed, the control relay energizes and its
associated contacts change state. The green pilot light is now ON and the red lamp is OFF. When
the STOP button is pressed, the contacts return to their resting state, the red pilot light is ON, and
the green switches OFF.
Relay logic design
In many cases, it is possible to design a relay logic diagram directly from the narrative
description of a control event sequence. In general, the following suggestions apply to designing
a relay logic diagram:
1. Define the process to be controlled.
2. Draw a sketch of the operation process. Make sure all the components of the system are
present in the drawing.
3. Determine the sequence of operations to be performed. List the sequence of operational steps
in as much detail as possible. Write out the sequence in sentences, or put them in table form.
4. Write the relay logic diagram from the sequence of operations.
Applications
A major application of relay logic is the control of routing and signalling on railways. This safety
critical application uses interlocking to ensure conflicting routes can never be selected and helps
reduce accidents. Elevators are another common application - large relay logic circuits were
employed from the 1930s onward to replace the human elevator operator, but have been progressively superseded with modern solid-state controls in recent years.
Machine control
Machine-to-Machine
Machine-to-machine (M2M) refers to technologies that allow both wireless and wired systems to communicate with other devices of the same ability. M2M uses a device (such as a sensor or meter) to capture an event (such as temperature, inventory level, etc.), which is relayed through a network (wireless, wired or hybrid) to an application (software program), that translates the captured event into meaningful information (for example, items need to be restocked). Such communication was originally accomplished by having a remote network of machines relay information back to a central hub for analysis, which would then be rerouted into a system like a personal computer.
However, modern M2M communication has expanded beyond a one-to-one connection and changed into a system of networks that transmits data to personal appliances. The expansion of wireless networks across the world has made it far easier for M2M communication to take place and has lessened the amount of power and time necessary for information to be communicated between machines. These networks also allow an array of new business opportunities and connections between consumers and producers in terms of the products being sold.
Relay logic
Relay logic is a method of controlling industrial electronic circuits by using relays and contacts.
Ladder logic
Main article: ladder logic
The schematic diagrams for relay logic circuits are often called line diagrams, because the inputs and outputs are essentially drawn in a series of lines. A relay logic circuit is an electrical network consisting of lines, or rungs, in which each line or rung must have continuity to enable the output device. A typical circuit consists of a number of rungs, with each rung controlling an output. This output is controlled by a combination of input or output conditions, such as input switches and control relays. The conditions that represent the inputs are connected in series, parallel, or series-parallel to obtain the logic required to drive the output. The relay logic circuit forms an electrical schematic diagram for the control of input and output devices. Relay logic diagrams represent the physical interconnection of devices. The basic format for relay logic diagrams is as follows:
1. The two vertical lines that connect all devices on the relay logic diagram are labeled L1 and L2. The space between L1 and L2 represents the voltage of the control circuit.
2. Output devices are always connected to L2. Any electrical overloads that are to be included must be shown between the output device and L2; otherwise, the output device must be the last component before L2.
3. Control devices are always shown between L1 and the output device. Control devices may be
connected either in series or in parallel with each other.
4. Devices which perform a STOP function are usually connected in series, while devices that
perform a START function are connected in parallel.
5. Electrical devices are shown in their normal conditions. An NC contact would be shown as
normally closed, and an NO contact would appear as a normally open device. All contacts
associated with a device will change state when the device is energized.
Figure 1 shows a typical relay logic diagram. In this circuit, a STOP/START station is used to
control two pilot lights. When the START button is pressed, the control relay energizes and its
associated contacts change state. The green pilot light is now ON and the red lamp is OFF. When
the STOP button is pressed, the contacts return to their resting state, the red pilot light is ON, and
the green switches OFF.
Relay logic design
In many cases, it is possible to design a relay logic diagram directly from the narrative
description of a control event sequence. In general, the following suggestions apply to designing
a relay logic diagram:
1. Define the process to be controlled.
2. Draw a sketch of the operation process. Make sure all the components of the system are
present in the drawing.
3. Determine the sequence of operations to be performed. List the sequence of operational steps
in as much detail as possible. Write out the sequence in sentences, or put them in table form.
4. Write the relay logic diagram from the sequence of operations.
Applications
A major application of relay logic is the control of routing and signalling on railways. This safety
critical application uses interlocking to ensure conflicting routes can never be selected and helps
reduce accidents. Elevators are another common application - large relay logic circuits were
employed from the 1930s onward to replace the human elevator operator, but have been progressively superseded with modern solid-state controls in recent years.