215
ifm
Programming Manual BasicController relay CR0431 v03.03.00
05 / 2018
Terms and abbreviations
>
EUC
EUC =
E
quipment
U
nder
C
ontrol.
EUC is equipment, machinery, apparatus or plant used for manufacturing, process, transportation,
medical or other activities (
→ IEC 61508-4, section 3.2.3). Therefore, the EUC is the set of all
equipment, machinery, apparatus or plant that gives rise to hazards for which the safety-related
system is required.
If any reasonably foreseeable action or inaction leads to
→hazards with an intolerable risk arising from
the EUC, then safety functions are necessary to achieve or maintain a safe state for the EUC. These
safety functions are performed by one or more safety-related systems.
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F
FiFo
FIFO (
F
irst
I
n,
F
irst
O
ut) = Operating principle of the stack memory: The data packet that was written
into the stack memory first, will also be read first. Each identifier has such a buffer (queue).
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Flash memory
Flash ROM (or flash EPROM or flash memory) combines the advantages of semiconductor memory
and hard disks. Similar to a hard disk, the data are however written and deleted blockwise in data
blocks up to 64, 128, 256, 1024, ... bytes at the same time.
Advantages of flash memories
The stored data are maintained even if there is no supply voltage.
Due to the absence of moving parts, flash is noiseless and insensitive to shocks and magnetic
fields.
Disadvantages of flash memories
A storage cell can tolerate a limited number of write and delete processes:
• Multi-level cells: typ. 10 000 cycles
• Single level cells: typ. 100 000 cycles
Given that a write process writes memory blocks of between 16 and 128 Kbytes at the same time,
memory cells which require no change are used as well.
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FRAM
FRAM, or also FeRAM, means
Fe
rroelectric
R
andom
A
ccess
M
emory. The storage operation and
erasing operation is carried out by a polarisation change in a ferroelectric layer.
Advantages of FRAM as compared to conventional read-only memories:
• non-volatile,
• compatible with common EEPROMs, but:
• access time approx. 100 ns,
• nearly unlimited access cycles possible.
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H
Heartbeat
The participants regularly send short signals. In this way the other participants can verify if a
participant has failed.
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HMI
HMI =
H
uman
M
achine
I
nterface
Summary of Contents for BasicController CR0431
Page 228: ...228 10 Notizen Notes Notes...
