Glossary
Page 34
Version FELD-V2002.02
PROFIBUS manual
ISO:
International Organization for Standardization
LSPM2, SPM2:
PROFIBUS ASICs for simple slave applications.
Mandatory
services:
These are the services that every PROFIBUS station must
support.
Master class 1:
A master that implements the transfer of the user data. Usually a
PLC or a PC.
Master class 2:
Master for control/commissioning and configuration tasks. In
general it can support not only DP cyclical services but also
DVP1 acyclical services.
Min_Slave_
Interval
Time between 2 poll cycles in master/slave communication. A
typical value used to be about 2 ms, but the use of powerful
ASICs has since reduced this time to the region of a few
μ
s
. The
user can also employ the Min_Slave_Interval to control time-
intensive user processes.
max
tsdr
:
The latest time within which the slave must respond to a request
by the master. In this case the value lies between 60 and 800 Tbit
depending on the baud rate.
min
tsdr
:
The time that the slave must wait before it is allowed to respond
to a request by the master. Specified as 11 Tbit in the standard.
Octet:
Term used in EN 50 170. An octet equals exactly eight bits.
OLM:
Optical Link Module. OLMs can be used to set up redundant
transmission paths. They can also be used for switching between
RS-485 and optical fiber technology.
Optional services: These services may be performed by a PROFIBUS station in
addition to the mandatory services (see SYNC and FREEZE).
OSI:
Open Systems Interconnection
PROFIBUS DP
PROFIBUS Decentralized Peripherals. PROFIBUS protocol
whose strengths lie in high-speed cyclical data transfer. (Cyclical
data transfer only)
PROFIBUS DPV1 PROFIBUS DP with additional functions. Includes the DP
functions but also recognizes acyclical data transfer in addition to
cyclical data transfer. This mode is relatively complex for the
programmer of the master.
PROFIBUS FMS Field Message Specification. Transmission protocol on the
PROFIBUS whose strengths tend to lie in object-oriented data
transfer because of the powerful services it offers. FMS can be
used in common with DP. Not supported by the DIGIFORCE
®
type 9310.