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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 |
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| (see chapter 2.5.1) |
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4504 | 2 | Selected physical unit of AO2 | 3, 4 | U/A/S | none |
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| (see chapter 2.5.1) |
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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 |
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Format: | Hex |
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Value: | 0x001000 |
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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 |
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| function | access | access |
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| code |
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4378 | 6 | Measurement | Measurement | Measurement | 3, 4, 16 | U/A/S | S |
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| value at | value at | value at |
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| Min Output | Max Output | Mid Output |
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| Current (4 mA) | Current (20 | Current (12 |
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| for AO1 | mA) for AO1 | mA) for AO1 |
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4506 | 6 | Measurement | Measurement | Measurement | 3, 4, 16 | U/A/S | S |
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| value at | value at | value at |
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| Min Output | Max Output | Mid Output |
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| Current (4 mA) | Current (20 | Current (12 |
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| for AO2 | mA) for AO2 | mA) for AO2 |
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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 |
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Format: | Float | Float | Float |
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Value: | 3 | 10 | 7 |
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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 |