Chapter 5 Flashcards
1
Q
two different ways of memory structures for ladder logic
A
- rack based system (address)
- tag based system
2
Q
tag
A
user friendly name for a memory location, no fixed address
3
Q
first pass bit/status bit
A
first bit that makes once when go into run mode and then it turns off
4
Q
memory space can be divided into two types of files
A
- program files: part of processor memory that stores user ladder logic
- data files: store info needed to carry out user program
5
Q
program files
A
- system functions (0): contains system related info
- reserved (1): reserved by processor
- main ladder (2): ladder logic
- subroutine ladder (3-255): created by user
6
Q
data files
A
- output (0): output terminals
- input (1): input terminals
- status (2): controller operation info
- bit (3): internal relay logic storage
- timer (4): timer info
- counter (5): counter info
- control (6): stores length, pointer position, and status bit for special instructions
- integer (7): whole numbers
- float (8): fractional data
7
Q
scans
A
scans from left to right (horizontal)
8
Q
logical continuity
A
for a output to make or become true, there must be a continuous path of true conditional instructions
9
Q
length of scan depends on:
A
- speed of processor module
- length of ladder program
- type of instructions executed
- actual ladder true/false conditions
10
Q
plc programming language types
A
- textural language (instruction list, structured text)
- graphical language (ladder diagram, functional block diagram, sequential function chart)
11
Q
scan process
A
- read input module
- solve ladder program
- transfer to output module
12
Q
three fundamental symbols for ladder logic
A
- examine if closed (N.O. contact)
- examine if open (N.C. contact)
- output energize (relay coil)
13
Q
limitations to ladder logic
A
- can not have a branch within another branch
- no vertical contacts
- there must be logic continuity from left to right only
14
Q
file for storage and addressing of internal output bits
A
B3
