pH ARC Sensors Modbus RTU Programmer’s Manual (EPHUM011)

2.4.5.5Reading the Selected Physical Unit for Analog Interface

Start

Number of

Reg1 / Reg2

Modbus

Read

Write

register

registers

 

function code

access

access

4376

2

Selected physical unit of AO1

3, 4

U/A/S

none

 

 

(see chapter 2.5.1)

 

 

 

4504

2

Selected physical unit of AO2

3, 4

U/A/S

none

 

 

(see chapter 2.5.1)

 

 

 

Figure 2.4.5.5.1: Definition of register 4376 / 4504.

Command: Avail unit AO1

Modbus address: 4376

Length: 2

Type: 3

Read

Parameter:

Available unit

 

 

 

 

 

 

Format:

Hex

 

 

 

 

 

 

Value:

0x001000

 

 

 

 

 

 

Figure 2.4.5.5.2: Example to read the selected unit of the selected PMC of AO1. The value returned is “0x001000”, accordingly, the unit is pH. The physical unit for PMC is defined in Reg. 2090 or 2410 and applies automatically for 4-20 mA output.

2.4.5.6Defining the Measurement Values for 4, 12 and 20 mA Output

Start

Number of

Reg1 / Reg2

Reg3 / Reg4

Reg5 / Reg6

Modbus

Read

Write

register

registers

 

 

 

function

access

access

 

 

 

 

 

code

 

 

4378

6

Measurement

Measurement

Measurement

3, 4, 16

U/A/S

S

 

 

value at

value at

value at

 

 

 

 

 

Min Output

Max Output

Mid Output

 

 

 

 

 

Current (4 mA)

Current (20

Current (12

 

 

 

 

 

for AO1

mA) for AO1

mA) for AO1

 

 

 

4506

6

Measurement

Measurement

Measurement

3, 4, 16

U/A/S

S

 

 

value at

value at

value at

 

 

 

 

 

Min Output

Max Output

Mid Output

 

 

 

 

 

Current (4 mA)

Current (20

Current (12

 

 

 

 

 

for AO2

mA) for AO2

mA) for AO2

 

 

 

Figure 2.4.5.6.1: Definition of register 4378 / 4506.

Command: MinMaxMid value AO1

Modbus address: 4378

Length: 6

Type: 16

Write

Parameter:

Min value

Max value

Mid value

 

 

Format:

Float

Float

Float

 

 

 

Value:

3

10

7

 

 

 

Figure 2.4.5.6.2: Example to set the min value to 3 (for 4 mA), the max value to 10 (for 20 mA) and the mid value to 7 (for 12 mA). The corresponding physical unit can be read in register 4376 / 4504 and in 2090 / 2410.

Note:

Mid current must always be defined. However, in linear output mode, the mid current value has no physical meaning and will not affect the 4-20 mA output.

624300/01

page 13 / 67

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Hamilton Electronics EPHUM011 manual Reading the Selected Physical Unit for Analog Interface, 0x001000