ABB AC 800F

13 Glossary
13-12 *) Component of the Freelance 2000 System
Profibus data retention All telegrams have a hamming distance HD=4. Complies with IEC 870-5-
1. Special start/end bit, non-slip synchronization, parity bit and control
byte
Profibus module FI 830F The Profibus module is a Profibus-DP master according to DIN 19245,
for rapid data exchange with decentralized peripherals (DP) in
manufacturing.
Protective earth
→ Safety grounding
-R-
Rack *
)
Framework for the process station modules; used for the central unit and
the I/O unit(s).
Rack ID *
)
Identification code of the rack. Setable with the coding switch at the link
module back. → Coding switch
RAM Random Access Memory
Read/write working memory of the CPU module or PC central unit. The
CPU module RAM is battery-buffered. →CMOS RAM
Rated voltage value Voltage for which the voltage separation of the module was calculated
and specified. In the final quality control of manufacturing (routine check
test) the modules are submitted for a short time to a much higher test
voltage to assure their insulating property. → Test voltage
Real-time clock When using the AC 800F for the first time, the real-time clock must be
adjusted (set time and date). This data is retained, provided that the
device is battery-buffered. If the possible deviation should be too
important, it is recommended to use a radio clock.
Redundancy To improve the availability of a process control system, some of its
components like the power supply or CPU can be provided as redundant
units, i.e. twice. If one of them should fail, the redundant unit, which has
been passive up to that moment, takes over the function and, thus,
prevents a total system failure. Redundancy is also implemented for the
AC 800F.
Redundancy link Point-to-point connection (Ethernet) between Primary and Secondary for
matching the data.
Repeater Couples two Ethernet segments. The number of possible repeaters on an
Ethernet is limited.
Reset switch Push-button switch on the AC 800F power supply module
Resets the AC 800F, i. e. initiates a cold start, when pressed for more
than 4 seconds. Mounted recessed. Can only be pressed with a "tool"
(e.g. ball-point pen, paper clip, etc.).
RFI Radio Frequency Interference
RFI suppression Measures taken to limit/suppress radio frequency interference from the
Freelance 2000 system which might impair radio services or other units.