Siemens SITRANS F M Intermag 2, Руководство по эксплуатации

Страница: 92 / 130

Operation
5-44
SITRANS FM Intermag 2 Flow Transmitter
Operating Manual - A5E00102775-03
5.4.1 Cyclic Data Traffic
Cyclic data transmission serves for fast exchange of useful data
between a class 1 master (control system or PLC) and the slave
(SITRANS FM).
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 GSD, section
5.4.1.3 ).
5.4.1.1 Input Data (from Slave to Master)
The input data are useful data (measured values) which are
transferred from the device to the master in the following format with
the ”Data_Exchange” service:
Every measured value consists of 5 bytes which are made up of a
floating point value according to IEEE-754 (4 bytes) for the
measured value itself and the corresponding measured value status
(1 byte). In the PROFIBUS telegram, the measured value is
transmitted first and then the corresponding status.
Byte Bit y
No.
7 (MSB) 6 5 4 3 2 1 0 (LSB)
1 VZ E
2
7
E
2
6
E
2
5
E
2
4
E
2
3
E
2
2
E
2
1
2 E
2
0
M
2
-1
M
2
-2
M
2
-3
M
2
-4
M
2
-5
M
2
-6
M
2
-7
3 M
2
-8
M
2
-9
M
2
-10
M
2
-11
M
2
-12
M
2
-13
M
2
-14
M
2
-15
4 M
2
-16
M
2
-17
M
2
-18
M
2
-19
M
2
-20
M
2
-21
M
2
-22
M
2
-23
VZ: sign: 0 positive, 1 negative E: Exponent M: Mantissa
Table 5-5 Measured value format
Byte
N
Bit
y
No.
7 (MSB) 6 5 4 3 2 1 0 (LSB)
5 Quality Substatus Limits
Table 5-6 Status byte format