E+E Elektronik EE431, Руководство пользователя

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User Manual EE431
Duct and Immersion Temperature Sensor | 17
5.4.7. Modbus RTU Example
Example of Modbus RTU command for reading the Temperature (float value) T = 26,953624 °C from the register
0x3EA.
Device EE431; Modbus address 66 [42 in HEX]
Reference document (chapter 6.3):
http://www.modbus.org/docs/Modbus_Application_Protocol_V1_1b.pdf .
Read the temperature (FLOAT32) T from register address 0x3EA :
Master (e.g. PLC) Temperature Sensor
Request [Hex]:
Modbus
address Function
code
Starting
address Hi
Starting
address Lo
Qty. of
registers Hi
Qty. of
registers Lo
CRC
42 03 03 EA 00 02 EB 48
Response [Hex]:
Modbus
address Function
code
Byte
count
Register 1
value Hi
Register 1
value Lo
Register 2
value Hi
Register 2
value Lo
CRC
42 03 04 A1 06 41 D7 3B 04
Fig. 8 Example temperature query
Decoding of floating point values:
Floating point values are stored according to IEEE754. The byte pairs 1, 2 and 3, 4 are transformed as follows
(numbers taken from T reading Modbus request/response example, Fig. 8):
Modbus response [Hex]
Register 1 Hi Register 1 Lo Register 2 Hi Register 2 Lo
A1 06 41 D7
MMMMMMMM MMMMMMMM SEEEEEEE EMMMMMMM
Fig. 9 Modbus response
IEEE754
Register 2 Hi Register 2 Lo Register 1 Hi Register 1 Lo
41 D7 A1 06
0100 0001 1101 0111 1010 0001 0000 0110
SEEE EEEE EMMM MMMM MMMM MMMM MMMM MMMM
Decimal value: 26.953624725341796875
Fig. 10 Data representation according to IEEE754
6 Maintenance and Service
6.1 Calibration and Adjustment
6.1.1. Definitions
Calibration : The specimen is compared with a reference and its deviation from the reference is documented.
Adjustment
: The specimen is brought in line with the reference.