7 Modbus protocol (RTU)
7.1 Prerequisites
Connection via RS-485 interface
Transmission parameters data bits: 8; parity: none; stop bits: 1 (8N1)
Transmission speed 9600 bps
Operating parameter "Measurement |"Automatic" Combined with OTT netDL: activated
Note:
When connecting the OTT ecoN to an IP Datalogger OTT netDL, the OTT netDL configuration is limited on using
Modbus function "Read Holding Registers" (0x03).
7.2 "Read Holding Registers" (0x03) / "Write Multiple Register" (0x10) functions
1)
Byte sequence: AB CD (Big Endian)
Register name
Register-
number Type
Value range
Factory
setting
Access-
mode
Unit
Bus address
0000
unsigned word 1 … 247
1
R/W
–
Serial number
0010
unsigned word 10 Byte; ASCII-Format
–
R
–
Firmware version
0015
unsigned word 10 Byte; ASCII-Format
–
R
–
Measured value
NO
3
-N
scaled value
1000
1500
float
1)
1 mm: 0.5 … 60
10 mm: 0.05 … 6
R
[
mg/L]
Measured value NO
3
scaled value
1002
1502
float
1)
1 mm: 2.2 … 266
10 mm: 0.22 … 26.6
R
[
mg/L]
Spectral quality
index SQI
scaled value
1004
1504
float
1)
0 … 28 000
R
[1]
Light intensity
212 nm; RefA
scaled value
1006
1506
float
1)
0 … 28 000
R
[1]
Light intensity
254 nm; RefB
scaled value
1008
1508
float
1)
0 … 28 000
R
[1]
Light intensity
360 nm; RefC
scaled value
1010
1510
float
1)
0 … 28 000
R
[1]
Light intensity
reference diode, RefD
scaled value
1012
1512
float
1)
0 … 28 000
R
[1]
18
