Design - Siemens SITRANS F MASS 2100 Operating Instructions Manual

Description

3.4 Design

Features
The SITRANS F Modbus RTU communication complies with the Modbus Serial Line Protocol.
Among other things this implies a master / slave protocol at level 2 of the OSI model. A node (the
master) issues explicit commands to one of the slave nodes and processes responses. Slave
nodes will not transmit data without a request from the master node, and do not communicate
with other slaves.
Modbus is a mono master system, only one master can be connected at a time.
Unicast communication mode
In unicast mode (master/slave mode) the master sends a request to a specific slave device and
waits a specified time for a response.
Figure 3-1
Modbus Frame
The Modbus frame is shown below and is valid for both requests and responses.
Table 3-1
SLAVE ADDRESS
1 Byte
References
For further information, please refer to the following specification and guidelines available at
the Modbus Organization (http://www.modbus.org/) website
1. Serial Line Specification & Implementation guide
2. Application Protocol Specification
3.4 Design
The SITRANS FC flowmeters use the Coriolis principle to measure flow and is available in a
compact and a remote design.
18
Master
Slave
Unicast Mode
Modbus Frame
FUNCTION MODE
1 Byte
Slave Slave
DATA
0 to 252 Bytes
SITRANS MASS 2100 & FC300 (FCT010/DSL)
Operating Instructions, 06/2020, A5E39788682-AB
CRC
2 Bytes