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pH ARC Sensors Modbus RTU Programmer’s Manual (EPHUM011)
624300/01 page 44 / 67
2.7.4 Reading the Calibration Status
2.7.4.1 Reading the Calibration Status of CP1 and CP2
A standard calibration is not always successful. In order to analyze what has gone wrong, two different
calibration status registers can be read:
Register 5158 for CP1
Register 5190 for CP2
Note
Registers 5158 and 5190 contain the same information!
Bit # Hex value Definition
0 (LSB) 0x00000001 CP1: difference between CP1 and CP2 < pH 1.0
1 0x00000002 CP1: no matching calibration standard
2 0x00000004 CP1: actual temperature reading is too low
3 0x00000008 CP1: actual temperature reading is too high
4 0x00000010 CP1: temperature reading during calibration is not stable
5 0x00000020 CP1: offset a pH 7 is too low or slope is too low
6 0x00000040 CP1: offset a pH 7 is too high or slope is too high
7 0x00000080 CP1: pH reading during calibration is not stable
8 0x00000100 CP2: difference between CP2 and CP1 < pH 1.0
9 0x00000200 CP2: no matching calibration standard
10 0x00000400 CP2: actual temperature reading is too low
11 0x00000800 CP2: actual temperature reading is too high
12 0x00001000 CP2: temperature reading during calibration is not stable
13 0x00002000 CP2: offset a pH 7 is too low or slope is too low
14 0x00004000 CP2: offset a pH 7 is too high or slope is too high
15 0x00008000 CP2: pH reading during calibration is not stable
… not available
24 0x01000000 CP6: out of calibration range
25 0x02000000 CP6: out of range
26 0x04000000 CP6: active
27 0x08000000 CP6: initial measurement
28 0x10000000 CP6: assigned
not available
30 0x40000000 CP2: incorrect measurement unit
31 0x80000000 CP1: incorrect measurement unit
Figure 2.7.4.1.1: Definition of the status for register 5158, 5190 and 5318 (see Figure 2.7.4.1.2 and
2.7.4.2.1).
Start
register
Number of
registers
Reg1 / Reg2 Reg3 / Reg4 Reg5 / Reg6 Modbus
function
code
Read
access
Write
access
5158 6 Status CP1
(see figure
2.7.4.1.1)
Physical unit of
the last
successful
calibration CP1
(always pH)
pH value of the
last successful
calibration CP1
3, 4 U/A/S none
5190 6 Status CP2
(see figure
2.7.4.1.1)
Physical unit of
the last
successful
calibration CP2
(always pH)
pH value of the
last successful
calibration CP2
3, 4 U/A/S none
Figure 2.7.4.1.2: Definition of register 5158 for CP1 and register 5190 for CP2.