Process Image - WAGO 750 Series Manual

32 • 750-461/020-000 [2 AI NTC 20kOhm]

Process Image

2.1.3.6 Process Image
Some fieldbus systems can process input channel status information by means
of a status byte.
This status byte can be displayed via the WAGO-I/O-CHECK 2 start-up and
diagnostic tool. However, processing via the coupler / controller is optional,
which means that accessing or parsing the status information depends on the
fieldbus system.
Attention
The representation of the process data of some I/O modules or their variations
in the process image depends on the fieldbus coupler/-controller used. Please
take this information as well as the particular design of the respective
control/status bytes from the section "Fieldbus Specific Design of the Process
Data" included in the description concerning the process image of the
corresponding coupler/controller.
The analog input modules 750-461/020-000 transmit 16-bit measured values
per channel as well as 8 optional status bits to the coupler/controller.
To evaluate the NTC 20kOhm resistance sensors the measured values of the
resistance are converted and sent as temperature values.
All temperature values are represented in a standard numeric format. The
possible numerical range matches the defined temperature range of the sensors
from -30 °C to +130 °C.
In the NTC 20kOhm setting, the temperature values of the sensors are
represented with a resolution of 1 digit per 0.1 °C within a word (16 bits).
Thus, 0 °C corresponds to the numeric value 0x0000 and 100 °C to 0x03E8
(dec. 1000).
Temperature values below 0 °C are represented in two's complement binary
form.
perature
<ca -30.0
>ca 130.0
1)
The measured value can exceed the range from decimal –300 to 1300 until the limitation
applies.
Tem- Resis-
tance
°C kΩ
>414.70 '0010.0001.0011.0100'
-30.0 414.70 '1111.1110.1101.0100'
0.0 70.20 '0000.0000.0000.0000'
25.0 20.00 '0000.0000.1111.1010'
50.0 6.72 '0000.0001.1111.0100'
100.0 1.12 '0000.0011.1110.1000'
130.0 0.46 '0000.0101.0001.0100'
< 0.46 '1000.0000.0000.0001'
Temperature values below 0 °C are represented in two's complement binary form.
750-461/020-000
1)
Numerical value
binary hex.
0x2134
0xFED4
0x0000
0x00FA
0x01F4
0x03E8
0x0514
0x8001
Status- LED
byte Error
dec. Hex. AI 1, 2
8500 0x42 on
-300 0x00 off
0 0x00 off
250 0x00 off
500 0x00 off
1000 0x00 off
1300 0x00 off
-32767 0x41 on
WAGO-I/O-SYSTEM 750
I/O Modules