MPU Series B
Ultrasonic Gas Flow Meter
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PRD-0000022543 Rev. 00D
Page 15 of 28
MNKS008 0.0 (4/08)
4.2.2. ModBus Write Message Example
In this example the flow computer performs the following task:
- Write temperature and pressure from the MPU Series B
The database objects used for pressure and temperature from an
external source are object numbers 10000 and 10001. These have the
ModBus addresses 20000 and 20002. These registers are written with
ONE message with function code 16. Figure 4 below shows the
contents of this message.
01
10
4E
20
00
04
Node
no.
Function
code
Pressure - 100 barA
1st register
address
08
42
C8
00
Temp - 37.5 barA
00
Number of
16-bit values
Byte
Count
42
16
00
00
Figure 4 - ModBus Write Message Example
The reply from the MPU Series B will be on the format described in
the figure below.
01
10
4E
20
00
04
Node
no.
Function
code
1st register
address
Number of
16-bit values written
Figure 5 - ModBus Write Reply Message Example
The message contains a copy of the first 6 bytes of the request
message.
