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pH ARC Sensors Modbus RTU Programmer’s Manual (EPHUM011)
624300/01 page 9 / 67
2.4 Configuration of the Analog Interfaces
2.4.1 Available Analog Interfaces
A pH ARC Sensor has two individual physical analog interfaces that have identical functionalities, but
can be configured independently from each other.
Analog Output Interface 1 (AO1)
Analog Output Interface 2 (AO2)
The number of analog interfaces is defined in register 4320.
Start
register
Number of
registers
Reg1 / Reg2 Modbus
function code
Read
access
Write
access
4320 2 Available analog interfaces 3, 4 U/A/S none
Figure 2.4.1.1: Definition of register 4320.
Command: Avail analog interfaces
Modbus address: 4320 Length: 2 Type: 3
Read
Parameter: Available analog
interfaces
Format: Hex
Value:
0x03
Figure 2.4.1.2: Example to read the available analog interfaces. The answer is “0x03”meaning that
there exists an Analog Interface 1 (AO1) and an Analog Interface 2 (AO2).
2.4.2 Available Analog Interface Modes
With register 4322, the available analog interface modes for AO1 and AO2 are defined
Start
register
Number of
registers
Reg1 /
Reg2
Reg3 /
Reg4
Reg5 /
Reg6
Reg7 /
Reg8
Modbus
function
code
Read
access
Write
access
4322 8 Available
Analog
Interface
Modes for
AO1
Available
Analog
Interface
Modes
for AO2
reserved reserved 3,4 U/A/S none
Figure 2.4.2.1: Definition of register 4322. It defines the analog interface modes available for AO1 and
AO2. The analog interface modes are described in Figure 2.4.2.2.
Code
(Hex)
Analog Interface
Mode
Description
0x00 4-20 mA inactive Analog interface deactivated
0x01 4-20 mA fixed Set to a constant output value for current loop testing
0x02 4-20 mA linear Linear output of measurement (PMC1 / 6)
0x04 4-20 mA bilinear Bilinear output of measurement (PMC1 / 6)
Figure 2.4.2.2: Definition of the analog interface modes, valid for both AO1 and AO2.
Command: Analog Interface Modes
Modbus address: 4322 Length: 8 Type: 3
Read
Parameter: Available Analog
Interface Modes for
AO1
Available Analog
Interface Modes for
AO2
reserved reserved
Format: Hex Hex Hex Hex
Value:
0x07 0x07 0x0 0x0
Figure 2.4.2.3: Example to read register 4322: all modes defined in figure 2.4.2.2 are available for both
AO1 and AO2.