The personal computer is the most commonly used programming device for PLCs
Comparators in the SLC 500 PLC must always be used on the input or the right side of the ladder rung
DeviceNet and ControlNet use scanner modules to interface to the PLC
The IEC 61131 ladder logic symbol library has only input contacts and output symbols available
The accumulator of an SLC 500 PLC counter changes one count for every false-to-true transition at the input to the counter.
DeviceNet, ControlNet, and Internet/IP are all international standards used by PLC vendors
PLCs conform to an international standard called IEC 61131
The PLC standard does not include the ladder-logic programming language because most United states manufacturers of PLC have their own proprietary ladder-logic language
PLC modules get their power and data communications over the backplane
To communicate with sensors, The PLC uses a SERCOS interface
A valve stack would be a likely device connected to ControlNet, but another PLC is usually never connected to ControlNet
In rack/slot addressing, the slot location of the PLC processor is indicated in the address
The DeviceNet module is used to communicate primarily with motor controllers
ControlNet uses the Product/consumer model, is highly deterministic and repeatable, and is ideal for interfacing with smart sensors
Sequential function charts is a PLC language that is very similar to Grafcet
The Machine architecture for a PLC is the same as that used for a Personal computer, with the exception of a hard drive
In the Aleen Bradley RS Logix PLC, all variables are called tags
Instruction list is a PLC language that is very similar to Pascal
The TOF timer for SLC 500 PLC turns the done bit off when the accumulator reaches the preset value
Relay ladder logic and ladder logic for PLC program are similar because the output symbols and control logic are on a rung, but they are different because the PLC ladder never has field-device switch contacts located in it
Scan time is the time it takes for PLC to read all input data and write that data into an input register