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UMG 96-PA / UMG 96-PA-MID / UMG 96-PA-MID+
13.12 Communication in the bus system
13.12.1 RS-485
The device sends and receives data via the
RS-485 interface. For example, the device re-
ceives data from the parameter and measured
value list via a MODBUS RTU protocol with CRC
check.
Modbus functions (slave)
03 Read Holding Registers
04 Read Input Registers
06 Preset Single Register
16 (10Hex) Preset Multiple Registers
23 (17Hex) Read/Write 4X Registers
The order of the bytes is high before low byte
(Motorola format).
Transmission parameters
Data bits:
8
Parity:
odd
even
none (1 stop bit)
none (2 stop bits)
Stop bits (UMG 96-PA): 1 / 2
External stop bits:
1 / 2
Number formats
Short
16 bit (-2
15
.. 2
15
-1)
Float
32 bit (IEEE 754)
For further information on configuring the RS-485
interface on the device, see section „12.3 Com-
munication“ on page 38. For information on the
interface, see section „8.2 RS-485 interface“ on
page 28.
Example: Reading the voltage L1-N
The voltage L1-N is stored in the parameter
and measured value list at address 19000 in the
FLOAT format.
In this example 01 is assumed as the device
address.
The "Query Message" then looks as follows:
Designation
Hex Comment
Device address
01
Address=1
Function
03
"Read Holding Reg"
Start address Hi 4A
19000dec = 4A38hex
Start address Lo 38
No. of values Hi
00
2dec = 0002hex
No. of values Lo 02
Error check
(CRC)
-
The "response" of the device can then look as
follows:
Designation
Hex Comment
Device address
01
Address=1
Function
03
Byte counter
06
Data
00
00hex=00dec
Data
E6
E6hex=230dec
Error check
(CRC)
-
The voltage L1-N sent from address 19000 is
230 V.