31 of 38
cRIO LVDT 9312 Module
Technical Description
Issue
05
24/05/2022
5.2
LVDT9312
D
RIVER
-I
NSTRUCTIONS
The LVDT9312
driver instructions are defined within the type definition file „USRCMD.ctl“.
The instruction names
correlate with an identification number which is given in brackets (), below.
Command execution requires a specific execution time and varies due to asynchronous processing principles.
Hence a timeout should be defined for an instruction call which by default is 40.000.000 system ticks (equal to 1
second for a 40MHz FPGA). When no timeout is connected to the input terminal of the Function-VI, the default
timeout value is active. To specify a timeout other than the default value, the input must be connected to a new
timeout value. Note that specifying a timeout less than 40.000.000 has no effect because the default value cannot
be reduced. If an instruction takes longer than the specified timeout, a fault is generated from the driver (refer
to the drivers fault codes).
Instruction [U8]:
Tx-Data [U8]:
Receive-Data [I16]:
Data Sink:
Read Position
(1)
no data
LVDT Position [RAW]
LVDT Controller
This instruction reads the actual LVDT position. The data scaling is binary data within the range of -32768 to 32767
equal to -1 to 1. It takes 24us (+/-1us) to receive the position data.
The maximum position sampling rate for cyclic reading is 40kHz. To calculate the resolver position in engineering
units use the following equation:
15
2
1
=
DATA
Position
Note that dividing by 2
15
equals a logical shift of 15.
Instruction [U8]:
Tx-Data [U8]:
Receive-Data [U16]:
Data Sink:
Read Amplitude
(3)
no data
Excit. Amplitude. [mV
RMS
]
LVDT Controller
This instruction reads the programmed amplitude of the excitation voltage. The return data format is a 16bit
engineering value in [mV
RMS
].
