Hamilton Electronics EPHUM011 2.5.2 Primary Measurement Channel 1 (pH)

pH ARC SensorsModbus RTU Programmer’s Manual (EPHUM011)
624300/01 page 20/ 67
2.5.2 Primary Measurement Channel 1 (pH)
2.5.2.1 Descriptionof PMC1
In register 2080, a plain text ASCII description of PMC1 is given.
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register Number of registers Reg1…Reg8 16 ASCII characters Modbus function code Read access Write access
2080 8 Description ofPMC1 3, 4 U/A/S none
Figure 2.5.2.1.1:Definition of register 2080.
Command: PMC 1 text Modbusaddress: 2080 Length: 8Type: 3Read
Parameter: Text
Format: Character
Value: pH
Figure 2.5.2.1.2: Examplet o read the description. It is “pH”.
2.5.2.2 Selecting the Physical Unit for PMC1
In register 2088,the available physical units for this channel are defined.
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register Number of registers Reg1/ Reg2 (bitwise defined) Modbus function code Read access Write access
2088 2 Available physicalunits of PMC1 3, 4 U/A/S none
Figure 2.5.2.2.1:Definition of register 2088.
Command: PMC1available units Modbusaddress: 2088 Length: 2Type: 3Read
Parameter: Units
Format: Hex
Value: 0x201000
Figure 2.5.2.2.2: Example to read the available physical units of PMC1: pH (0x001000) + mV
(0x200000),total 0x201000.
In register 2090,the active physical unit for this channel can be selected, by choosing one of the
physical units that are defined in register 2088.
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register Number of registers Reg1/ Reg2 (bitwise defined) Modbus function code Read access Write access
2090 2 Selected activephysical unit for the
PMC1 16 none S
Figure 2.5.2.2.3:Definition of register 2090. Only one bit can be set.
Command: PMC1 set unit Modbusaddress: 2090 Length: 2Type: 16 Write
Parameter: Unit
Format: Hex
Value: 0x1000
Figure 2.5.2.2.4:Example to set the physical unit of PMC1 to pH (0x1000).
Attention:
Changingt hephysical unit has also an influence on the output of AO1 / AO2, as the same physical unit
is activef or the analogoutputs. All limits of the 4-20 mA analog output have to be redefined after
changing the physicalunit!