BECKHOFF KL3311 - Manual (Page 17)

Register Description
KL3311, KL3312, KL3314 and KL3302 15
the terminal contacts), a gain register (R21) is implemented, which is
identical for both sets of registers.
Compensation can be carried out as follows:
First, the offset is carried out with 0V input voltage, reference temperature
deactivated and linearization switched off. 0xF100 is entered in the feature
register. This is followed by gain compensation with a maximum voltage of
125 mV (typical value: 70 mV). For this terminal setting with deactivated
manufacturer scaling, the voltage is displayed with 4
μV per digit.
Gain and offset compensation of the thermocouple voltage is carried out
separately for each channel.
In the next step, the temperature of the reference point is compensated. To
this end, a thermocouple has to be selected via the feature register, and
reference point temperature compensation must be active (R32 0x1006
type K). With short-circuited inputs (0 V), the temperature of the terminal
contacts is determined, and the temperature output by the terminal
(measured via an internal temperature sensor) is set accordingly (via R21).
The reference point temperature only has to be calibrated once for each
terminal, i.e. R21 is identical for both channels.
Register communication
Register access via
process data exchange
Bit 7=1
bin
: Register mode
If bit 7 of the control byte is set, then the first two bytes of the user data are
not used for exchanging process data, but are written into or read from the
terminal's register set.
Bit 6=0
bin
: read
Bit 6=1
bin
: write
Bit 6 of the control byte specifies whether a register should be read or
written. If bit 6 is not set, then a register is read out without modifying it.
The value can then be taken from the input process image.
If bit 6 is set, then the user data is written into a register. As soon as the
status byte has supplied an acknowledgement in the input process image,
the procedure is completed (see example).
Bit 0 to 5: Address The address of the register that is to be addressed is entered into bits 0 to
5 of the control byte.
Control byte in
register mode
MSB
REG=1 W/R A5 A4 A3 A2 A1 A0
REG = 0
bin
: Process data exchange
REG = 1
bin
: Access to register structure
W/R = 0
bin
: Read register
W/R = 1
bin
: Write register
A5...A0 = register address
Address bits A5 to A0 can be used to address a total of 64 registers.