5.2.5 - Feedback [U6 Datasheet]
Published on LabJack (https://labjack.com)

Home > Support > Datasheets > U6 Datasheet > 5 - Low-level Function Reference > 5.2 - Low-Level Functions > 5.2.5 - Feedback

5.2.5 - Feedback [U6 Datasheet]

Feedback Overview

A flexible function that handles all command/response functionality. One or more IOTypes are used to perform a single write/read or multiple writes/reads.

Note that the general protocol described in "Section 5.1":/support/u6/users-guide/5.1 defines byte 2 of an extended command as the number of data words, which is the number of words in a packet beyond the first 3 (a word is 2 bytes). Also note that the overall size of a packet must be an even number of bytes, so in this case an extra 0x00 is added to the end of the command and/or response if needed to accomplish this.

Since this command has a flexible size, byte 2 will vary. For instance, if a single IOType of PortStateRead (d26) is passed, byte 2 would be equal to 1 for the command and 3 for the response. If a single IOType of LED (d9) is passed, an extra 0 must be added to the command to make the packet have an even number of bytes, and byte 2 would be equal to 2. The response would also need an extra 0 to be even, and byte 2 would be equal to 2.

Command:  
Byte  
0 Checksum8
1 0xF8
2 0.5 + Number of Data Words (IOTypes and Data)
3 0x00
4 Checksum16 (LSB)
5 Checksum16 (MSB)
6 Echo
7-63 IOTypes and Data
   
Response:  
Byte  
0 Checksum8
1 0xF8
2 1.5 + Number of Data Words (IOTypes and Data)
3 0x00
4 Checksum16 (LSB)
5 Checksum16 (MSB)
6 Errorcode
7 ErrorFrame
8 Echo
9-63 Data
  • IOTypes & Data: One or more IOTypes can be passed in a single command, up to the maximum packet size. More info about the available IOTypes is below. In the outgoing command each IOType is passed and accompanied by 0 or more data bytes. In the incoming response, only data bytes are returned without the IOTypes.
  • Echo: This byte is simply echoed back in the response. A host application might pass sequential numbers to ensure the responses are in order and associated with the proper command.
  • ErrorFrame: If Errorcode is not zero, this parameter indicates which IOType caused the error. For instance, if the 3rd passed IOType caused the error, the ErrorFrame would be equal to 3. Also note that data is only returned for IOTypes before the one that caused the error, so if any IOType causes an error the overall function response will have less bytes than expected.

IOTypes for Feedback Command:

Name IOType (dec) WriteBytes ReadBytes
AIN 1 3 2
AIN24 2 4 3
AIN24AR 3 4 5
WaitShort 5 2 0
WaitLong 6 2 0
LED 9 2 0
BitStateRead 10 2 1
BitStateWrite 11 2 0
BitDirRead 12 2 1
BitDirWrite 13 2 0
PortStateRead 26 1 3
PortStateWrite 27 7 0
PortDirRead 28 1 3
PortDirWrite 29 7 0
DAC0 (8-bit) 34 2 0
DAC1 (8-bit) 35 2 0
DAC0 (16-bit) 38 3 0
DAC1 (16-bit) 39 3 0
Timer0 42 4 4
Timer0Config 43 4 0
Timer1 44 4 4
Timer1Config 45 4 0
Timer2 46 4 4
Timer2Config 47 4 0
Timer3 48 4 4
Timer3Config 49 4 0
Counter0 54 2 4
Counter1 55 2 4

5.2.5.1 - AIN: IOType = 1 [U6 Datasheet]

AIN, 3 Command Bytes:  
0 IOType=1
1 PositiveChannel
2 Reserved
   
2 Response Bytes:  
0 AIN LSB
1 AIN MSB

This is the U3 style IOType to get a single analog input reading. It is available for compatibility, but to make full use of the U6 the new AIN24 IOType should be used.

Note: Do not call this IO type while streaming.

  • PositiveChannel: 0-143 for AIN0-AIN143. 14 is the internal temperature sensor and 15 is internal GND.
  • NegativeChannel: 0, 15, or 199 signifies a single-ended reading. For differential readings this should be positive channel plus one, where the positive channel is an even number from 0-142.
  • AIN LSB & MSB: Analog input reading is returned as a 16-bit value (always unsigned).

5.2.5.2 - AIN24: IOType = 2 [U6 Datasheet]

AIN24, 4 Command Bytes: 
0 IOType=2
1 PositiveChannel
2 Bits 0-3: ResolutionIndex
  Bits 4-7: GainIndex
3 Bits 0-2: SettlingFactor
  Bit 7: Differential
   
3 Response Bytes: 
0 AIN LSB
1 AIN Bits 8-15
2 AIN MSB

This IOType returns a single analog input reading. If using the autorange feature, the AIN24AR IOType in the following Section should be used instead.

Note: Do not call this IO type while streaming.

  • PositiveChannel: 0-143 for AIN0-AIN143. 14 is the internal temperature sensor and 15 is internal GND.
  • ResolutionIndex: 0=default, 1-8 for high-speed ADC, 9-12 for high-res ADC on U6-Pro.
  • GainIndex: 0=x1, 1=x10, 2=x100, 3=x1000.
  • SettlingFactor: 0=Auto, 1=20us, 2=50us, 3=100us, 4=200us, 5=500us, 6=1ms, 7=2ms, 8=5ms, 9=10ms. This is the time between when the muxes are changed and the reading is sampled. "Auto" ensures enough settling for any gain and resolution with source impedances less than at least 1 kohms.
  • Differential: If this bit is set, a differential reading is done where the negative channel is PositiveChannel+1.
  • AIN bytes: Analog input reading is returned as a 24-bit value (always unsigned).

5.2.5.3 - AIN24AR: IOType = 3 [U6 Datasheet]

AIN24AR, 4 Command Bytes: 
0 IOType=3
1 PositiveChannel
2 Bits 0-3: ResolutionIndex
  Bits 4-7: GainIndex
3 Bits 0-2: SettlingFactor
  Bit 7: Differential
   
5 Response Bytes: 
0 AIN LSB
1 AIN Bits 8-15
2 AIN MSB
3 Bits 0-3: ResolutionIndex
  Bits 4-7: Gain Index
4 Status

This IOType returns a single analog input reading. Also returns the actual resolution and gain used for the reading.

Note: Do not call this IO type while streaming.

  • PositiveChannel: 0-143 for AIN0-AIN143. 14 is the internal temperature sensor and 15 is internal GND.
  • ResolutionIndex: 0=default, 1-8 for high-speed ADC, 9-12 for high-res ADC on U6-Pro. Value in the response is the actual resolution setting used for the reading.
  • GainIndex: 0=x1, 1=x10, 2=x100, 3=x1000, 15=autorange. Value in the response is the actual gain setting used for the reading.
  • SettlingFactor: 0=Auto, 1=20us, 2=50us, 3=100us, 4=200us, 5=500us, 6=1ms, 7=2ms, 8=5ms, 9=10ms.
  • Differential: If this bit is set, a differential reading is done where the negative channel is PositiveChannel+1.
  • AIN bytes: Analog input reading is returned as a 24-bit value (always unsigned).
  • Status: Reserved for future use.

5.2.5.4 - WaitShort: IOType=5 [U6 Datasheet]

WaitShort, 2 Command Bytes: 
0 IOType=5
1 Time (* 64 us)
   
0 Response Bytes: 
   

This IOType provides a way to add a delay during execution of the Feedback function. The typical use would be putting this IOType in between IOTypes that set a digital output line high and low, thus providing a simple way to create a pulse. Note that this IOType uses the same internal timer as stream mode, so cannot be used while streaming.

  • Time: This value (0-255) is multiplied by 64 microseconds to determine the delay.

5.2.5.5 - WaitLong: IOType=6 [U6 Datasheet]

Table 5.2.5.5-1. WaitLong Command Response

WaitLong, 2 Command Bytes: 
0 IOType=6
1 Time (*16 ms)
   
0 Response Bytes: 

This IOType provides a way to add a delay during execution of the Feedback function. The typical use would be putting this IOType in between IOTypes that set a digital output line high and low, thus providing a simple way to create a pulse. Note that this IOType uses the same internal timer as stream mode, so cannot be used while streaming.

  • Time: This value (0-255) is multiplied by 16384 microseconds to determine the delay.

5.2.5.6 - LED: IOType=9 [U6 Datasheet]

Table 5.2.5.6-1. LED Command Response

LED, 2 Command Bytes: 
0 IOType = 9
1 State
   
0 Response Bytes: 

This IOType simply turns the status LED on or off.

  • State: 1=On, 0=Off.

5.2.5.7 - BitStateRead: IOType=10 [U6 Datasheet]

Table 5.2.5.7-1. BitStateRead Command Response

BitStateRead, 2 Command Bytes: 
0 IOType = 10
1 Bits 0-4: IONumber
   
1 Response Byte: 
0 Bit 0: State

This IOType reads the state of a single bit of digital I/O. Note that CIO0-2 & MIO0-2 are shared, so to write/read MIO0-2 use channel numbers 16-18.  Only lines configured as digital (not analog) return valid readings.

  • IO Number: 0-7=FIO, 8-15=EIO, or 16-19=CIO.
  • State: 1=High, 0=Low.

5.2.5.8 - BitStateWrite: IOType=11 [U6 Datasheet]

Table 5.2.5.6-1. BitStateRead Command Response

BitStateWrite, 2 Command Bytes: 
0 IOType = 11
1 Bits 0-4: IO Number
  Bit 7: State
0 Response Bytes: 

This IOType writes the state of a single bit of digital I/O. Note that CIO0-2 & MIO0-2 are shared, so to write/read MIO0-2 use channel numbers 16-18.  The direction of the specified line is forced to output.

  • IO Number: 0-7=FIO, 8-15=EIO, or 16-19=CIO.
  • State: 1=High, 0=Low.

5.2.5.9 - BitDirRead: IOType=12 [U6 Datasheet]

Table 5.2.5.9-1. BitDirRead Command Response

BitDirRead, 2 Command Bytes: 
0 IOType = 12
1 Bits 0-4: IO Number
   
1 Response Byte: 
0 Bit 0: Direction

This IOType reads the direction of a single bit of digital I/O. Note that CIO0-2 & MIO0-2 are shared, so to write/read MIO0-2 use channel numbers 16-18.  This is the digital direction only, and does not provide any information as to whether the line is configured as digital or analog.

  • IO Number: 0-7=FIO, 8-15=EIO, or 16-19=CIO.
  • Direction: 1=Output, 0=Input.

5.2.5.10 - BitDirWrite: IOType=13 [U6 Datasheet]

Table 5.2.5.10-1. BitDirWrite Command Response

BitDirRead, 2 Command Bytes: 
0 IOType = 13
1 Bits 0-4: IO Number
   Bit 7: Direction
0 Response Bytes: 
   

This IOType writes the direction of a single bit of digital I/O. Note that CIO0-2 & MIO0-2 are shared, so to write/read MIO0-2 use channel numbers 16-18.  

  • IO Number: 0-7=FIO, 8-15=EIO, or 16-19=CIO.
  • Direction: 1=Output, 0=Input.

5.2.5.11 - PortStateRead: IOType=26 [U6 Datasheet]

Table 5.2.5.11-1. PortStateRead Command Response

PortStateRead, 1 Command Byte: 
0 IOType = 26
   
3 Response Bytes: 
0-2 State

This IOType reads the state of all digital I/O, where 0-7=FIO, 8-15=EIO, and 16-19=CIO. Note that CIO0-2 and MIO0-2 are shared, so for reads of MIO0-2 look at 16-18. Only lines configured as digital (not analog) return valid readings.

  • State: Each bit of this value corresponds to the specified bit of I/O such that 1=High and 0=Low. If all are low, State=d0. If all 20 standard digital I/O are high, State=d1048575. If FIO0-FIO2 are high, EIO0-EIO2 are high, CIO0 is high, and all other I/O are low (b00010000011100000111), State=d67335.

5.2.5.12 - PortStateWrite: IOType=27 [U6 Datasheet]

Table 5.2.5.12-1. PortStateWrite Command Response

PortStateWrite, 7 Command Bytes: 
0 IOType = 27
1-3 WriteMask
4-6 State
   
0 Response Bytes: 

This IOType writes the state of all digital I/O, where 0-7=FIO, 8-15=EIO, and 16-19=CIO. Note that CIO0-2 and MIO0-2 are shared, so for writes to MIO0-2 use channel numbers 16-18. The direction of the selected lines is forced to output.

  • WriteMask: Each bit specifies whether to update the corresponding bit of I/O.
  • State: Each bit of this value corresponds to the specified bit of I/O such that 1=High and 0=Low. To set all low, State=d0. To set all 20 standard digital I/O high, State=d1048575. To set FIO0-FIO2 high, EIO0-EIO2 high, CIO0 high, and all other I/O low (b00010000011100000111), State=d67335.

5.2.5.13 - PortDirRead: IOType=28 [U6 Datasheet]

Table 5.2.5.13-1. PortDirRead Command Response

PortDirRead, 1 Command Byte: 
0 IOType = 28
   
3 Response Bytes: 
0-2 Direction

This IOType reads the directions of all digital I/O, where 0-7=FIO, 8-15=EIO, and 16-19=CIO. Note that CIO0-2 and MIO0-2 are shared, so for reads of MIO0-2 look at 16-18. These are the digital directions only, and do not provide any information as to whether the lines are configured as digital or analog.

  • Direction: Each bit of this value corresponds to the specified bit of I/O such that 1=Output and 0=Input. If all are input, Direction=d0. If all 20 standard digital I/O are output, Direction=d1048575. If FIO0-FIO2 are output, EIO0-EIO2 are output, CIO0 is output, and all other I/O are input (b00010000011100000111), Direction=d67335.

5.2.5.14 - PortDirWrite: IOType=29 [U6 Datasheet]

Table 5.2.5.12-1. PortDirWrite Command Response

PortStateWrite, 7 Command Bytes: 
0 IOType = 29
1-3 WriteMask
4-6 Direction
   
0 Response Bytes: 
    

This IOType writes the direction of all digital I/O, where 0-7=FIO, 8-15=EIO, and 16-19=CIO. Note that CIO0-2 and MIO0-2 are shared, so for writes to MIO0-2 use channel numbers 16-18.

  • WriteMask: Each bit specifies whether to update the corresponding bit of I/O.
  • Direction: Each bit of this value corresponds to the specified bit of I/O such that 1=Output and 0=Input. To configure all as input, Direction=d0. For all 20 standard digital I/O as output, Direction=d1048575. To configure FIO0-FIO2 as output, EIO0-EIO2 as output, CIO0 as output, and all other I/O as input (b00010000011100000111), Direction=d67335.

5.2.5.15 - DAC# (8-bit): IOType=34,25 [U6 Datasheet]

Table 5.2.5.15-1. DAC 8-bit Command Response

DAC# (8-bit), 2 Command Bytes: 
0 IOType = 34, 35
1 Value
   
0 Response Bytes: 
    

This IOType will set the value of a single analog output. Use IOType 34 to set DAC0 and 35 to set DAC1. We recommend using the 16-bit IOType when using the U6.

  • Value: Valid values are: 0 to 255, where 255 (0xFF) will result in the maximum possible output.

5.2.5.16 - DAC# (16-bit): IOType=38,39 [U6 Datasheet]

Table 5.2.5.16-1. DAC 16 bit Command Response

DAC# (16-bit), 3 Command Bytes: 
0 IOType = 38, 39
1 Value LSB
2 Value MSB
   
0 Response Bytes: 
    

This IOType will set the value of a single analog output. Use IOType 38 to set DAC0 and 39 to set DAC1.

  • Value: The value will be truncated to 12-bits; the lower four bits will be discarded. Valid values are: 0 to 65535, where 65520 - 65535 (0xFFF0 - 0xFFFF) will result in the maximum possible output.

5.2.5.17 - Timer#: IOType=42,44,46,48 [U6 Datasheet]

Table 5.2.5.17-1. Timer Command Response

Timer#, 4 Command Bytes: 
0 IOType = 42, 44, 46, 48
1 Bit 0: UpdateReset
2 Value LSB
3 Value MSB
   
4 Response Bytes: 
0 Timer LSB
1 Timer
2 Timer
3 Timer MSB
   

This IOType provides the ability to update/reset a given timer, and read the timer value.

  • Value: These values are only updated if the UpdateReset bit is 1. The meaning of this parameter varies with the timer mode.
  • Timer: Returns the value from the timer module. This is the value before reset (if reset was done).

5.2.5.18 - Timer#Config: IOType = 43, 45, 47, 49 [U6 Datasheet]

Table 5.2.5.18-1. TimerConfig Command Response

Timer#Config, 4 Command Bytes: 
0 IOType = 43, 45, 47, 49
1 TimerMode
2 Value LSB
3 Value MSB
   
0 Response Bytes: 
   

This IOType configures a particular timer.

  • TimerMode: See Section 2.9 for more information about the available modes.
  • Value: The meaning of this parameter varies with the timer mode.

5.2.5.19 - Counter#: IOType = 54, 55 [U6 Datasheet]

Table 5.2.5.19-1. Counter Command Response

Counter#, 2 Command Bytes: 
0 IOType = 54, 55
1 Bit 0: Reset
   
4 Response Bytes: 
0 Counter LSB
1 Counter
2 Counter
3 Counter MSB

This IOType reads a hardware counter, and optionally can do a reset.

  • Reset: Setting this bit resets the counter to 0 after reading.
  • Counter: Returns the current count from the counter if enabled. This is the value before reset (if reset was done).