YSI DIQ/S 182 XT-4-MOD - Manual (Page 122)

Modbus connection System 182 XT-4
7 - 6 ba76028e01 02/2012
Query and response
telegram
Data transmission takes place via query and response telegrams. The
form of the telegrams is determined by the Modbus RTU protocol.
The Modbus master transmits a query telegram with a Modbus
command to the Modbus slave (here, the DIQ/S 182 XT-4-MOD). The
Modbus slave transmits a response telegram with the requested data
from the sensor data block or an error message.
Supported
Modbus commands
The DIQ/S 182 XT-4-MOD provides the data block for read access
only. Writing Modbus commands are not carried out.
7.4.2 Sensor administration under Modbus
Preparation of the IQ S ENSOR N ET for communication with the Modbus
may require, e.g. the following:
 Creating an IQ S
ENSOR N ET system with specific assignment of
sensor numbers to sensors
 Creating several IQ S
ENSOR N ET systems with the identical
assignment of sensor numbers to sensors
 Changing the order of the sensors in an already installed system
Creating the assignment
of sensor numbers
You want to install an IQ S ENSOR N ET system and, at the same time,
create a specific sequence of sensor number assignments to the
sensors.
Modbus commands Command code
Read Input Register 04h
Read Discrete Inputs 02h
Read Holding Register 03h
Read Coils 01h
1 Carry out a system start without any sensors (see section
3.12).
2 Connect the sensors to the system in the required order. With
each sensor wait until the system has recognized the sensor.