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Measurements reading (function 04h)
Function code 04h allows to read the values measured by the instrument.
The input register address containing the first quantity and the number of consecutive
quantities to be read are indicated in the request data field.
Since, in the protocol, registers are numbered starting from 1, but data are addressed
starting from 0, a register address is equal to the register number decremented by 1.
The instrument replies with the value of the requested quantities. It is not allowed to
read quantities that are not measured by the instrument model.
Consequently, the Function and Data fields of command and response assume the
following format:
Command
Value
Function:
04h
Data:
0000h to FFFFh
0001h to 007Dh
Response
Value
Function:
04h
Data:
2 x N
A measurement value is stored in a 16-bit register and consequently always requires
a 2-byte length. The most significant byte precedes the least significant one.
The following table lists the available quantities with their register number.
Tab. 8.D: Input registers
Register
number
0001
Temperature in °C (x10)
0002
Temperature in °F (x10)
0003
Relative humidity in % (x10)
0004
Dewpoint in °C (x10)
0005
CO
in ppm
2
If the request involves the reading of at least one parameter that is not included in
Table 8.D, the instrument will answer with the following error message:
Response
Value
Function:
84h
Data:
02h
Length
1 byte
2 bytes
2 bytes
Length
1 byte
1 byte
2 x N bytes
Quantity
Length
1 byte
1 byte
- 51 -
Description
Measurements reading command
First quantity address
Number of quantities to be read (N)
Description
Measurements reading command
Number of bytes for the values
Measurements values
Format
16 bits
16 bits
16 bits unsigned
16 bits unsigned
16 bits unsigned
Description
Error in measurements reading
Operation involved an inexistent
parameter (Tab. 8.F page 59)
From
Notes
Ver.
FW
1.00
1.00
1.00
1.00
1.00
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