Hamilton Electronics EPHUM011 - Manual (Page 13)

pH ARC Sensors Modbus RTU Programmer ’ s Manual (EPHUM011)
624300/01 page 13 / 67
2.4.5.5 Reading the Selected Physical Unit for Analog Interface
Start
register Number of
registers Reg1 / Reg2 Modbus
function code Read
access Write
access
4376 2 Selected physical unit of AO1
(see chapter 2.5.1) 3, 4 U/A/S none
4504 2 Selected physical unit of AO2
(see chapter 2.5.1) 3, 4 U/A/S none
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
Format: Hex
Value: 0x001000
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.
2.4.5.6 Defining the Measurement Values for 4, 12 and 20 mA Output
Start
register Number of
registers Reg1 / Reg2 Reg3 / Reg4 Reg5 / Reg6 Modbus
function
code Read
access Write
access
4378 6 Measurement
value at
Min Output
Current (4 mA)
for AO1 Measurement
value at
Max Output
Current (20
mA) for AO1 Measurement
value at
Mid Output
Current (12
mA) for AO1 3, 4, 16 U/A/S S
4506 6 Measurement
value at
Min Output
Current (4 mA)
for AO2 Measurement
value at
Max Output
Current (20
mA) for AO2 Measurement
value at
Mid Output
Current (12
mA) for AO2 3, 4, 16 U/A/S S
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
Format: Float Float Float
Value: 3 10 7
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.