Receiving and interpreting of data returned from devices which use a binary communication protocol is done with the READ statement. The READ statement gets a message from the device, strips off the protocol frame and places the result in an internal buffer. Subcommands/operations following the READ keyword are used to copy values from the buffer into one or more variables of the device driver.
The READ statement by default works in 'little endian' mode. 16, 32 or 64 bit values are read from the buffer with the least significant byte first. Specifying BIGENDIAN mode reverses this byte order.
| INT8 p | The INT8 keyword, followed by a decimal position value, tells the driver that the next variable appearing in the argument list shall be filled from a single byte value at the given position (position zero denotes the first byte in the buffer). |
| INT16 p | The INT16 keyword, followed by a decimal position value, tells the driver that the next variable appearing in the argument list shall be filled from a two-byte value starting at the given position (position zero denotes the first byte in the buffer). The least significant byte of the number is read first unless BIGENDIAN was specified. |
| INT32 p | The INT32 keyword, followed by a decimal position value, tells the driver that the next variable appearing in the argument list shall be filled from a four-byte value starting at the given position (position zero denotes the first byte in the buffer). The least significant byte of the number is read first unless BIGENDIAN was specified. |
| INT64 p | The INT64 keyword, followed by a decimal position value, tells the driver that the next variable appearing in the argument list shall be filled from a eight-byte value starting at the given position (position zero denotes the first byte in the buffer). The least significant byte of the number is read first unless BIGENDIAN was specified. |
| BITS p : b : w | The BITS keyword tells the driver to read a 1 to 7 bit wide bit field from a certain byte in the buffer. In this case the position parameter consists of three values, separated by colons: |
position p addresses the byte within the buffer, |
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bitpos b defines the bit-number (0 to 7) of the least significant bit to read. |
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width w the number of bits which shall be copied from the buffer into the destination variable. |
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| FLOAT16 p | The FLOAT16 keyword, followed by a decimal position value, tells the driver that the next variable appearing in the argument list shall be filled from a half precision (16 bit) IEEE754 floating point value starting at the given position (position zero denotes the first byte in the buffer). The least significant byte of the number is read first unless BIGENDIAN was specified. |
| FLOAT32 p | The FLOAT32 keyword, followed by a decimal position value, tells the driver that the next variable appearing in the argument list shall be filled from a single precision (32 bit) IEEE754 floating point value starting at the given position (position zero denotes the first byte in the buffer). The least significant byte of the number is read first unless BIGENDIAN was specified. |
| FLOAT64 p | The FLOAT64 keyword, followed by a decimal position value, tells the driver that the next variable appearing in the argument list shall be filled from a double precision (32 bit) IEEE754 floating point value starting at the given position (position zero denotes the first byte in the buffer). The least significant byte of the number is read first unless BIGENDIAN was specified. |
| XLT table | The XLT keyword, followed by the name of an already defined table, tells the driver to translate the value read through this translation table from right to left. Chapter Using conversion tables gives more information about tables in general. |
| OFFSET o | The OFFSET keyword, followed by the (floating point) offset value, tells the driver to add the given offset to the value read. |
| SCALE s | The SCALE keyword, followed by the (floating point) scale factor, tells the driver to multiply value read with the given factor. |
| FUNCTION "name" | The FUNCTION keyword, followed by the name of the function as a quoted string, tells the driver to apply this function to the next variable before it is printed. The function name is extended by appending .txt to achieve the file name to read for the function definition. Chapter Function tables in I/O functions gives an extensive description about functions an how they are used. |
| BIGENDIAN | The BIGENDIAN keyword turns the byte order from little endian (LSB first) which is the default to big endian (MSB first). This applies to all values read after BIGENDIAN. |
| LITTLEENDIAN | The LITTLEENDIAN keyword turns the byte order back to 'little endian' (LSB first). This applies to all values read after LITTLEENDIAN. |
| variable-name | A variable name tells the driver to store the value read into the variable. |
Example
READ BIGENDIAN
INT32 1 SCALE 0.000001 tx.frequency
INT32 7 tx.mod.dataRate
INT32 11 SCALE 0.000001 refClkFreq
INT8 15 XLT T01 refClkSrc
INT8 16 XLT T02 tx.mod.type
INT8 17 XLT T03 tx.mod.fec
INT16 22 SCALE 0.1 tx.power
INT8 24 XLT T04 tx.on
INT8 24 XLT T04 internal.tx.on
INT8 25 XLT T05 tx.mod.cwMode
INT8 26 XLT T06 tx.mod.spectrumInvert
INT8 28 XLT T14 tx.ifc.hardware
INT8 29 XLT T06 tx.ifc.clockPhase
INT8 30 XLT T06 tx.ifc.dataPhase
INT8 31 XLT T07 tx.mod.clockSource
INT8 44 XLT T08 info.maskEnable
INT32 45 info.alarmMask
INT32 49 tx.mod.symbolRate
INT8 53 XLT T09 tx.ifc.framingMode
INT8 54 XLT T10 tx.mod.rollOff
INT8 55 XLT T11 config.control
INT8 57 XLT T12 modemTypeThe example above - taken from the Radyne DVB3030 modulator driver - shows the main settings READ statement of this driver. In one step almost all parameter settings are read.