Hamilton Electronics EPHUM011 manual Definitions of Calibration Points, CP1, CP2, 0x01000

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				function code	access	access
5152	6	Physical unit	Min value for	Max value for	3, 4	U/A/S	none
		currently	CP1 (in the	CP1 (in the
		active for	physical unit	physical unit
		CP1	as defined in	as defined in
			Reg1 and 2)	Reg1 and 2)
5184	6	Physical unit	Min value for	Max value for	3, 4	U/A/S	none
		currently	CP2 (in the	CP2 (in the
		active for	physical unit	physical unit
		CP2	as defined in	as defined in
			Reg1 and 2)	Reg1 and 2)

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
Format:	Hex	Float		Float
Value:	0x01000	0		0

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
Format:	Hex	Float		Float
Value:	0x01000	0		0

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
		pH	Temperature
		[pH/min]	[K/min]

Figure 2.7.2.1.4: Definition of register 5128.

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