Cyclic Data Traffic - Siemens SITRANS F TRANSMAG 2 Operating Instructions Manual

Shielding
• Only use shielded cables for the PROFIBUS connection. Any connection polarity is possible.
• The shield must be laid to cover all assigned terminal boxes, distributors up to the coupler or
link.
• The shield must be connected and fixed with the shield clamp.
• To achieve the best EMC performance, the unshielded wires should be as short as possible,
3-4 cm.
Note
The specified immunity and radiated emission are only guaranteed if the bus shielding is fully
effective. This includes connecting the shields to the metal connections of TRANSMAG 2, but
also laying the shields to the terminal compartment, distributor, DP/PA coupler or DP/PA link.
Terminators
To ensure trouble-free communication, the PROFIBUS must have a bus terminator at both ends.
This is usually already provided by the coupler or link at the control system end. An additional
bus terminator must be fitted at the remote bus end.
B.3

Cyclic Data Traffic

Cyclic data transmission serves for fast exchange of process data between a Master class 1
(control system or PLC) and the slave (SITRANS F M).
Up to four different measured values (= modules) can be transmitted cyclically from the device
to the control system as input data in one telegram with the "Data_Exchange" service.
The following measured values are available for selection in the given order:
1. Flow (volume or mass flow)
2. Totalizer (volume or mass) net
3. Totalizer (volume or mass) forwards
4. Totalizer (volume or mass) reverse
The output data are sent to the device with the cyclic request telegram. The number and type of
actually transferred data can be determined with the aid of the configuration data (see Device
Database File (GSD) (Page 114))
Acyclic data traffic
Acyclic data transmission is mainly used for remote control of devices, i.e. for transmitting
parameters during commissioning, maintenance, batch processes or for displaying variables
which are not included in the cyclic process data traffic.
Acyclic accesses can be carried out by Master class 1 (C1 connection) or Master class 2 (C2
connection). SITRANS F M supports up to 4 simultaneous C2 connections.
TRANSMAG 2 with MAG 911/E
Operating Instructions, 03/2021, A5E00102775-AC
Profibus Communication
B.3 Cyclic Data Traffic
107