PLC 1 Flashcards
Scans input conditions and executes user program to set output conditions
Processor
Lowers and stabilizes voltage used for electronics in PLC components.
Power supply
Printed circuit board with sockets that modules plug into
Backplane
Made of metal or plastic, this is the frame for most PLC systems
Chassis
Modules that are designed to connect the PLC to “real world” devices
I/O cards
Underlying systems that provide basic functions and services
Communications cards
Modules that connect the PLC to other systems and devices, such as variable speed drives and personal computers
Special purpose card
What do input cards do?
Convert signals from field devices to a signal for the processor
What are discrete modules used for?
Devices that have only one or two states
T/F any I/O point can be traced to a bit in processor memory
True
What designates the I/O type in an adress?
I: or O:
What systems provide communication between field devices and the processor?
The I/O system
What 6 advantages do PLC’s provide?
Increased reliability More flexibility Lower cost Communications capability Faster response time Easier to troubleshoot
What do output cards do?
They convert signals from the processor to signals for field devices
T/F Analog signals operate through only one value 4-20mA
False
T/F a programming terminal is required for the purpose if going online with the PLC to monitor I/O status
True
What is the primary function of a counter?
To keep track of how many
T/F it is possible to use a CTU and CTD instruction on the same address
False
T/F an RTO instruction needs an RES instruction
True
What program is used for allen bradleys PLC’s?
Rockwell’s RSLogix
What program is used to communicate between a PC and a PLC?
RSLinx
What is an example of an output?
A lamp
What is an example of an input?
A pushbutton
What is a channel configuration used for?
To set network addresses and connection speeds
What information does the I/O configuration provide?
The type and number of I/O cards
What should documentation include in a PLC system?
Device addresses, descriptions, and title pages
What does a complete scan cycle of a standard PLC include?
Self check, read I/O, solve user logic, and write outputs
What order does the PLC read logic in?
Top to bottom, left to right
What does XIC stand for
Examine if closed
What does an XIC instruction do?
Sets output to 1 if it examines a 1 at a set address
What does XIO stand for?
Examine if open
What does an XIO instruction do?
Sets output to 1 if it examines a 0 at a set address
What is the format for an address?
(File type)(File number):(Word)/(Bit)
What does OSR stand for?
One shot relay
What does OTE stand for?
Output energize
What does OTL stand for?
Output latch
What does OTU stand for?
Output unlatch
What does an OSR instruction do?
When the preceding instruction is true it sets its output bit to true for one cycle
What does an OTE instruction do?
When preceding instruction is true, it sets the output bit to 1
What does an OTL instruction do?
When preceding instrucion is true, it sets the output to 1 until it is unlatched
What does an OTU instruction do?
When preceding instruction is true, it unlatches a bit, setting it to 0
What does TON stand for?
Time on delay
What does TOF stand for?
Time off Delay
What does RTO stand for?
Retentive Time on Timer
What does RTF stand for?
Retentive timer false
What six values does each timer have?
Timer address, Timer base, preset value, accumulated value, enabled bit, and done bit
