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= Key 1
= Key 2
= Key 3
= Maximum or consumption = Minimum or supply.
Modbus RTU
With Modbus RTU protocol all addresses of the follo-
wing tables can be retrieved.
Table 1a
Measured values (floating point format)
Table 1b
Measured values (floating point format)
Table 2
Energy (floating point format)
Table 3a
Time information for min. and maximum
values and system time
Table 3b
Time information for min. and maximum
values and time of summer/ winter
changeover
Table 4
Avaraging times of mean values
Table 5
Internal control word
Table 6a
Measured values, integer format
Table 6b
Mean values, integer format
Table 6c
Maximum values, integer format
Table 6d
Minimum values, integer format
Table 7
Energy, integer format
Table 8
Scale of measured values, which are called
up in integer format
Table 9
In- and outputs
Table 10
EMAX-peak values
Transmission mode
RTU- Mode with CRC-Check.
Transmission parameters
Baud rate
RS232
: 9.6,19.2 and 38.4
RS485
: 9.6,19.2, 38.4, 57.6 and 115.2
Data bits
: 8
Parity
: none
Stop bits (UMG503)
: 2
Stop bits (extern)
: 1 or 2
Realized functions
Read Holding Register, function 03
Preset Single Register, function 06
Preset Multiple Registers, function 16
Data formats
The data are in the following formats at your disposal:
char:
1 Byte (0 .. 255)
word:
2 Byte (- 32 768 .. + 32 767)
long:
4 Byte (- 2 147 483 648 .. + 2 147 483 647)
The sequence of the bytes is high before low byte.
Example: Reading of system time
The system time is deposited under address 3000 in table
1. The system time is deposited in 6 bytes with year,
months, day, hours, minutes and second in the format
"char" = 0..255. The device address of the UMG 503 is
determined as address = 01.
The "Query Message" looks as follows:
Description
Hex
Comment
Device address
01
UMG503, Address = 1
Function
03
"Read Holding Register"
Start address Hi
0B
3000dez = 0BB8hex
Start address Lo
B8
No. of values Hi
00
6dez = 0006hex
no. of values Lo
06
Error Check
-
The "Response" of UMG503 can look as follows:
Description
Hex
Comment
Device address
01
UMG503, Address = 1
Function
03
Byte Counter
06
Data
00
Year =
00
hex
= 00
dez
= 20
00
dez
Data
0A
Month = 0A
hex
= 10
dez
= Oct.
Data
0C
Day = 0C
hex
= 12
dez
Data
0F
Hour = 0F
hex
= 15
dez
Data
1E
Minute = 1E
hex
= 30
dez
Data
0A
Second = 0A
hex
= 10
dez
Error Check (CRC) -
