pH ARC Sensors Modbus RTU Programmer’s Manual (EPHUM011)
2.7.2 Definitions of Calibration Points
2.7.2.1Calibration Points 1 and 2 (Standard Calibration)
The limits for the calibration point 1 are defined in register 5152, for calibration point 2 in register 5184.
Start | Number of | Reg1 / Reg2 | Reg3 / Reg4 | Reg5 / Reg6 | Modbus | Read | Write |
register | registers |
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| function code | access | access |
5152 | 6 | Physical unit | Min value for | Max value for | 3, 4 | U/A/S | none |
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| currently | CP1 (in the | CP1 (in the |
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| active for | physical unit | physical unit |
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| CP1 | as defined in | as defined in |
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| Reg1 and 2) | Reg1 and 2) |
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5184 | 6 | Physical unit | Min value for | Max value for | 3, 4 | U/A/S | none |
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| currently | CP2 (in the | CP2 (in the |
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| active for | physical unit | physical unit |
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| CP2 | as defined in | as defined in |
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| Reg1 and 2) | Reg1 and 2) |
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Figure 2.7.2.1.1: Definition of register 5152 for CP1 and 5184 for CP2.
Attention:
The only physical unit available for calibration is pH ! The physical unit defined in 5152, 5184 and 5312 for CP1, CP2 and CP6 is NOT linked to the physical unit defined for PMC1 in register 2090.
When performing a calibration while having the physical unit set to “mV”, the calibration status will report “CP1: incorrect measurement unit”or “CP2: incorrect measurement unit”(see figure 2.7.4.1.1).
Command: Calibration limits CP1 |
| Modbus address: 5152 | Length: 6 | Type: 3 | Read | ||
Parameter: | Unit | Min value | Max value |
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Format: | Hex | Float | Float |
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Value: | 0x01000 | 0 |
| 0 |
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Figure 2.7.2.1.2: Example to read the limits of CP1. Currently active physical unit is pH (0x01000). The min and max values are both 0, indicating, that calibration at CP1 can be performed only using defined calibration standards having discrete pH values.
Command: Calibration limits CP2 |
| Modbus address: 5184 | Length: 6 | Type: 3 | Read | ||
Parameter: | Unit | Min value | Max value |
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Format: | Hex | Float | Float |
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Value: | 0x01000 | 0 |
| 0 |
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Figure 2.7.2.1.3: Example to read the limits of CP2. The active physical unit is is pH (0x01000). The min and max values are both 0, indicating, that calibration at CP2 can be performed only using defined calibration standards having discrete pH values.
When initiating the calibration at CP1 and CP2, the measured pH and temperature have to be stable for at least 3 minutes. The stability criteria are defined in register 5128:
Start | Number of | Reg1 / Reg2 | Reg3 / Reg4 | Modbus | Read | Write |
register | registers | (Float) | (Float) | function code | access | access |
5128 | 4 | Max. Drift PMC1 | Max. Drift PMC6 | 3, 4, 16 | U/A/S | S |
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| pH | Temperature |
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| [pH/min] | [K/min] |
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Figure 2.7.2.1.4: Definition of register 5128.
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