Introducing Message-Based DAQ

Analog input scan operation 

C# Visual Basic 

// Read data from a scan operation 

DaqDevice MyDevice; 

String[] Devices; 

int Sample; 

int Channel; 

try 

{ 

// Get a list of message-based DAQ devices 

Devices = DaqDeviceManager.GetDeviceNames 

(DeviceNameFormat.NameAndSerno); 

// Get a DaqDevice object for device 0 

MyDevice = DaqDeviceManager.CreateDevice 

(Devices(0)); 

double[,] ScanData; 

String DataDisplay; 

// Configure the scan 

MyDevice.SendMessage 

("AISCAN:XFRMODE=BLOCKIO"); 


("AISCAN:RANGE=BIP10V"); 

MyDevice.SendMessage("AISCAN:LOWCHAN=0"); 

MyDevice.SendMessage("AISCAN:HIGHCHAN=3"); 

MyDevice.SendMessage("AISCAN:CAL=ENABLE"); 


("AISCAN:SCALE=ENABLE"); 

MyDevice.SendMessage("AISCAN:RATE=500"); 


("AISCAN:SAMPLES=256"); 

// Start the scan 

MyDevice.SendMessage("AISCAN:START"); 

// Read and display the scan data 

ScanData = MyDevice.ReadScanData(256); 

DataDisplay = String.Empty; 

For (Sample = 0; Sample < 256; Sample ++) 

{ 

} 

for (int j = 0; j < 4; j++) 

{ 

DataDisplay += ScanData[Channel, 

Sample].ToString("F04") + " "; 

} 

DataDisplay += Environment.NewLine; 

textBox1.Text = DataDisplay; 

} 

catch (Exception ex) 

{ 

} 

// handle error 

textBox1.Text = ex.Message; 

' Read data from a scan operation 

Dim MyDevice As DaqDevice 

Dim Devices As String() 

Dim Sample As Integer 

Dim Channel As Integer 

Try 

' Get a list of message-based DAQ devices 

Devices = DaqDeviceManager.GetDeviceNames_ 

(DeviceNameFormat.NameAndSerno) 

' Get a DaqDevice object for device 0 

MyDevice = DaqDeviceManager.CreateDevice 

(Devices(0)) 

Dim ScanData As Double(,) 

Dim DataDisplay As String 

' Configure the scan 

MyDevice.SendMessage("AISCAN:XFRMODE=BLOCKIO") 

MyDevice.SendMessage("AISCAN:RANGE=BIP10V") 

MyDevice.SendMessage("AISCAN:LOWCHAN=0") 

MyDevice.SendMessage("AISCAN:HIGHCHAN=3") 

MyDevice.SendMessage("AISCAN:CAL=ENABLE") 

MyDevice.SendMessage("AISCAN:SCALE=ENABLE") 

MyDevice.SendMessage("AISCAN:RATE=500") 

MyDevice.SendMessage("AISCAN:SAMPLES=256") 

' Start the scan 

MyDevice.SendMessage("AISCAN:START") 

' Read and display the scan data 

ScanData = MyDevice.ReadScanData(256) 

DataDisplay = String.Empty 

For Sample = 0 To 255 

For Channel = 0 To 3 

DataDisplay = String.Concat(DataDisplay, 

ScanData(Channel, _ Sample).ToString 

("F04") & " ") 

Next 

DataDisplay = String.Concat(DataDisplay, 

Environment.NewLine) 

Next 

TextBox1.Text = DataDisplay 

catch ex as Exception 

' handle error 

TextBox1.Text = Ex.Message 

End try 

Page 11 of 43

API message reference 

The API messages that you send to an MBD device are text-based commands. Each message pertains to a specific DAQ Component. 

A DAQ Component is a device element that encapsulates a DAQ subsystem which has multiple properties or commands associated 

with it. 

The DAQFlex API defines the following DAQ components. Click on a component name below for the string messages, device 

responses, and property values supported by the component. 

Component 

DEV 

AI 

AISCAN 

AITRIG 

AO 

DIO 

CTR 

Description 

Encapsulates device-level operations. 

Encapsulates single-point analog input operations. 

Encapsulates analog input scanning operations. 

Encapsulates analog input triggering operations. 

Encapsulates single-point analog output operations. 

Encapsulates digital I/O operations. 

Encapsulates counter input operations. 

Page 12 of 43

DEV 

Sets and gets device property values. 

Properties 

MFGSER, FWV, FLASHLED, ID, MFGCAL, RESET, DATATYPE 

The tables below list the messages used to get and set device parameters, the device response to each message, a description of the 

message, and the variable(s) the message may contain. 

Note: Refer to the device-specific information in the Hardware Reference section for the component properties and commands 

supported by each DAQ device. 

MFGSER 

Message Device response Description 

"?DEV:MFGSER" "DEV:MFGSER=value" Returns the manufacturer's device serial 

number. 

value = Serial number of the device 

Example: "DEV:MFGSER=00000001" 

FWV 


"?DEV:FWV" "DEV:FWV=value" Returns the firmware version 

value = Firmware version 

Example: "DEV:FWV=01.02" or 

"DEV:FWV=01.01.00f00" 

FLASHLED 


"DEV:FLASHLED/{n}" "DEV:FLASHLED" Flashes the device LED. 

n = a number indicating how many times to 

flash the device LED. 

Example: "DEV:FLASHLED/5" 

ID 


"DEV:ID=value" "DEV:ID" Sets the device ID. Enter up to 57 characters. 

value = device ID; value is set to MYDEVICE 

by default. 

Example: "DEV:ID=MYDEVICE" 

"?DEV:ID" "DEV:ID=value" Returns the ID set for the device. 

value = ID set for the device 

Page 13 of 43

MFGCAL 


"?DEV:MFGCAL" "DEV:MFGCAL=value" Returns the date and time in which the device 

was last calibrated. 

value = calibration date and time. 

Example: "DEV:MFGCAL=2009-03-14 

13:56:27" 

"?DEV:MFGCAL{YEAR}" "DEV:MFGCAL{YEAR}=value" Returns the year in which the device was last 

calibrated. 

YEAR = calibration year. 

Example: "DEV:MFGCAL{YEAR}=2009" 

"?DEV:MFGCAL{MONTH}" "DEV:MFGCAL{MONTH}=value" Returns the month in which the device was last 

calibrated. 

MONTH = calibration month 

Example: "DEV:MFGCAL{MONTH}=03" 

"?DEV:MFGCAL{DAY}" "DEV:MFGCAL{DAY}=value" Returns the day in which the device was last 

calibrated. 

DAY = calibration day 

Example: "DEV:MFGCAL{DAY}=14" 

"?DEV:MFGCAL{HOUR}" "DEV:MFGCAL{HOUR}=value" Returns the hour in which the device was last 

calibrated. 

HOUR = calibration hour 

Example: "DEV:MFGCAL{HOUR}=13" 

"?DEV:MFGCAL{MINUTE}" "DEV:MFGCAL{MINUTE}=value" Returns the minute in which the device was last 

calibrated. 

MINUTE = calibration minute 

Example: "DEV:MFGCAL{MINUTE}=56" 

"?DEV:MFGCAL{SECOND}" "DEV:MFGCAL{SECOND}=value" Returns the second in which the device was last 

calibrated. 

SECOND = calibration second 

Example: "DEV:MFGCAL{SECOND}=27" 

Page 14 of 43

RESET 


"DEV:RESET/value" 

"NO COMPONENT SET" when value 

is set to SYSTEM. 

"DEV:RESET" when value is set to 

DEFAULT. 

Resets the device or the default parameters. 

value = SYSTEM or DEFAULT 

SYSTEM resets the USB interface to the device 

(not recommended for use through the API). 

DEFAULT resets all device parameters to the 

default value. 

Example: "DEV:RESET/DEFAULT" 

DATATYPE 


"DEV:DATATYPE=value" "DEV:DATATYPE" Sets whether the datatype is included in raw 

data returns. 

value = ENABLE or DISABLE 

Example: "DEV:DATATYPE=ENABLE" 

• Refer to the RawData discussion in the Firmware specification for more information about DATATYPE. 

Page 15 of 43

CJC 


"?AI{ch}:CJC/format" "AI{ch}:CJC/format=value" Returns the CJC value in the specified format. 

format = DEGC, DEGF, KELVIN 

value = measured temperature 

Example: "?AI{0}:CJC/DEGC" 

STATUS 


"?AI:STATUS" "AI:STATUS=value" Returns the current ADC status of the AI 

operation. 

value = BUSY, ERROR, or READY 

SLOPE 


"?AI{ch}:SLOPE" "AI{ch}:SLOPE=value" Returns the calibration slope coefficient for the 

specified channel. 

ch = channel number 

value = calibration slope 

Example: "?AI{0}:SLOPE" 

OFFSET 


"?AI{ch}:OFFSET" "AI{ch}:OFFSET=value" Returns the calibration offset coefficient for the 

specified channel. 

ch = channel number 

value = calibration offset 

Example: "?AI{0}:OFFSET" 

CAL 1 


"AI:CAL=value" "AI:CAL" Enables or disables calibration of all A/D 

channels. 


Example: "AI:CAL=ENABLE" 

"?AI:CAL" "AI:CAL=value" Returns a value indicating whether the 

calibration coefficients will be applied to the raw 

A/D data. 


Example: "?AI:CAL" 

1 These messages are processed by the DAQFlex Software library, and are not sent to the device. 

Page 18 of 43

SCALE 1 


"AI:SCALE=value" "AI:SCALE" Enables or disables scaling of A/D channels. 


Example: "AI:SCALE=ENABLE" 

"?AI:SCALE" "AI:SCALE=value" Returns a value indicating whether scaling will 

be applied to the A/D channels. 



Working with the CAL and SCALE properties 

The ENABLE/DISABLE setting of the CAL and SCALE properties affect the kind of data that is returned: 

• CAL=DISABLE, SCALE=DISABLE 

If CAL and SCALE are both disabled, the data returned will be raw A/D integer values within the range of 0 to 2 res olution -1 of 

the device. If the calibration factors are stored on the device and applied to the data by the application software, the data 

range may be limited to well within these values. 

• CAL=ENABLE, SCALE=DISABLE 

When CAL is enabled and SCALE is disabled, the format of the analog data returned will depend on the type of calibration 

implemented. If the calibration factors are stored on the device and applied to the data by the application software, the data 

will be floating point values, not integer values, and may exceed the theoretical limits and include negative values and values 

above 2 res olution -1. 

• SCALE=ENABLE 

When SCALE is enabled, scaled floating point values are returned. The limits of the data will depend on the implementation of 

calibration, as described above. Data range limits may be a small percentage less than or greater than the full scale range 

selected for devices for which the calibration factors are stored on the device and applied to the data by the application 

software. 

Page 19 of 43

AISCAN 

Sets and gets property values when scanning analog input channels. 

Properties 

XFRMODE, RATE, SAMPLES, BUFSIZE, EXTPACER, HIGHCHAN, LOWCHAN, TRIG, RANGE, QUEUE, START, STOP, STATUS, COUNT, 

CAL, SCALE 





XFRMODE 


"AISCAN:XFRMODE=value" "AISCAN:XFRMODE" Sets the transfer mode for analog input scan 

data. 

value = SINGLEIO or BLOCKIO 

Example: "AISCAN:XFRMODE=BLOCKIO" 

"?AISCAN:XFRMODE" "AISCAN:XFRMODE=value" Returns the transfer mode that is set for the 

scan. 

value = SINGLEIO or BLOCKIO 

RATE 


"AISCAN:RATE=value" "AISCAN:RATE" Sets the A/D sampling rate in Hz for each 

channel. 

value = 0 to N 

Example: "AISCAN:RATE=1000" 

• If value is less than the device's minimum sampling rate, then the minimum rate is used. If value is greater than the 

device's maximum sampling rate, then the device's maximum sampling rate is used. 

• It is recommended to check the actual scan rate set using the "?AISCAN:RATE" query after setting the RATE. 

"?AISCAN:RATE" "AISCAN:RATE=value" Returns the A/D sampling rate in Hz for each 

channel. 

value = a value between the minimum and 

maximum rate that the device is capable of. 

• The value returned may not match the value requested using the "AISCAN:RATE=value" message due to device 

limitations. 

• If the value returned is at or near the device's maximum sampling rate, then sending other messages to the device 

should be kept to a minimum. Otherwise, there is a potential for a data overrun to occur. A data overrun occurs when 

the device fills its buffer with data faster than it is read back. 

Page 20 of 43

SAMPLES 


"AISCAN:SAMPLES=value" "AISCAN:SAMPLES" Sets the number of samples/channel to acquire 

in the scan. 

• A value of 0 results in a continuous scan. 


Example: "AISCAN:SAMPLES=1000" 

"?AISCAN:SAMPLES" "AISCAN:SAMPLES=value" Returns the number of samples/channel to 

acquire in the scan. 

• A value of 0 results in a continuous scan. 


BUFSIZE 


"AISCAN:BUFSIZE=value" "AISCAN:BUFSIZE" Sets the size in bytes of the buffer to be used 

for AISCAN. 

value = the size in bytes of the buffer. 

Example: "AISCAN:BUFSIZE=131072" 

• The default buffer size 1024000 bytes. This should be sufficient for most applications. The actual buffer size will always 

be an integer multiple of the device's maximum packet size. 

If this value is set, it should be at least the (number of bytes per sample) x (number of channels) x (sample count) for 

finite mode, and twice this value for continuous mode. 

"?AISCAN:BUFSIZE" "AISCAN:BUFSIZE=value" Returns the size of the buffer used for AISCAN. 

value = the size in bytes of the buffer. 

Page 21 of 43

EXTPACER 


"AISCAN:EXTPACER=value" "AISCAN:EXTPACER" Sets the configuration of the device's external 

pacer pin. 

value = ENABLE for most devices. 

Example: "AISCAN:EXTPACER=ENABLE" 

• Some devices support ENABLE/MASTER, ENABLE/SLAVE, ENABLE/GSLAVE, DISABLE/MASTER, or DISABLE/SLAVE. 

For devices which do not support a master and slave configuration, the /MASTER and /SLAVE designation is ignored. 

For devices which do not support disabling of the pacer or SYNC input (for example, the terminal is always enabled as 

either input or output), the DISABLE designation is invalid. 

When the optional portion of the message is omitted, the default is SLAVE. 

• Set to ENABLE if the device is paced using a continuous clock source, such as a generator. In this mode, the first clock 

pulse after setting up the scan is ignored in order to ensure adequate setup time for the first conversion. 

Set to ENABLE/GSLAVE if the device is paced from a DAQFlex Series device. In this mode, the first clock pulse after 

setting up the scan is held off to ensure adequate setup time for the first conversion. No pulses are ignored. 

• When the external pacer is enabled, the AISCAN:RATE property should be set to approximately what the external 

pacer rate will be, because internal transfer sizes are calculated using the rate and channel count. 

"?AISCAN:EXTPACER" "AISCAN:EXTPACER=value" Returns the configuration of the device's 

external pacer pin. 

value = ENABLE for most devices. 

• Some devices support ENABLE/MASTER, ENABLE/SLAVE, ENABLE/GSLAVE, DISABLE/MASTER, or DISABLE/SLAVE. 

HIGHCHAN 


"AISCAN:HIGHCHAN=value" "AISCAN:HIGHCHAN" Sets the last channel to include in the 

hardware-paced scan operation. 

value = channel number 

Example: "AISCAN:HIGHCHAN=3" 

"?AISCAN:HIGHCHAN" "AISCAN:HIGHCHAN=value" Returns the last channel to include in the 



Page 22 of 43

LOWCHAN 


"AISCAN:LOWCHAN=value" "AISCAN:LOWCHAN" Sets the first channel to include in the 



Example: "AISCAN:LOWCHAN=0" 

"?AISCAN:LOWCHAN" "AISCAN:LOWCHAN=value" Returns the first channel to include in the 



DEBUG 


"AISCAN:DEBUG=value" "AISCAN:DEBUG" Enables or disables the debug feature. 


Example: "AISCAN:DEBUG=ENABLE" 

• When the debug feature is enabled, the data returned by ReadScanData will be an incrementing count from 0 to the 

maximum value of the device's A/D. For 16-bit A/Ds this value is 65535. When this value is reached the count is reset 

to 0. 

"?AISCAN:DEBUG" "AISCAN:DEBUG=value" Returns the debug status. 


TRIG 


"AISCAN:TRIG=value" "AISCAN:TRIG" Enables or disables the trigger. 


Example: "AISCAN:TRIG=ENABLE" 

• If not set, TRIG is set to DISABLE by default. 

"?AISCAN:TRIG" "AISCAN:TRIG=value" Returns the trigger status. 


Page 23 of 43

eturned. 

value = range value (see values listed above) 

ch - channel number 

element - the element's position in the gain 

queue 

QUEUE 


"AISCAN:QUEUE=value" "AISCAN:QUEUE" Enables or disables the gain queue. 

value = ENABLE, DISABLE, or RESET 

RESET resets the queue count to 0, and 

disables the gain queue. 

Example: "AISCAN:QUEUE=ENABLE" 

"?AISCAN:QUEUE" "AISCAN:QUEUE=value" Reads whether the gain queue is used in the 

scanning operation. 


START 


"AISCAN:START" "AISCAN:STATUS=RUNNING" Starts an analog input scan. 

Example: "?AISCAN:START" 

STOP 


"AISCAN:STOP" "AISCAN:STATUS=IDLE" Stops an analog input scan. 

STATUS 


"?AISCAN:STATUS" "AISCAN:STATUS=value" Returns the status of the AISCAN operation. 

value = IDLE, RUNNING, or OVERRUN 

COUNT 1 


"?AISCAN:COUNT" "AISCAN:COUNT=value" Returns the number of samples per channel 

that have been acquired by the AISCAN 

operation. 

value = the number of samples per channel 

acquired. 

Example: "AISCAN:COUNT=64" 

1 This message is processed by the DAQFlex Software library, and is not sent to the device. 

Page 25 of 43

CAL 1 


"AISCAN:CAL=value" "AISCAN:CAL" Enables or disables calibration of the A/D data. 


Example: "AISCAN:CAL=ENABLE" 

"?AISCAN:CAL" "AISCAN:CAL=value" Returns a value indicating whether calibration 

coefficients will be applied to the raw A/D data. 


Example: "?AISCAN:CAL" 


SCALE 1 


"AISCAN:SCALE=value" "AISCAN:SCALE" Enables or disables scaling of the A/D data. 


Example: "AISCAN:SCALE=ENABLE" 

"?AISCAN:SCALE" "AISCAN:SCALE=value" Returns a value indicating whether scaling will 

be applied to the A/D data. 



Working with the CAL and SCALE properties 

The ENABLE/DISABLE setting of the CAL and SCALE properties affect the kind of data that is returned: 

• CAL=DISABLE, SCALE=DISABLE 

If CAL and SCALE are both disabled, the data returned will be raw A/D integer values within the range of 0 to 2 res olution -1 of 

the device. If the calibration factors are stored on the device and applied to the data by the application software, the data 

range may be limited to well within these values. 

• CAL=ENABLE, SCALE=DISABLE 

When CAL is enabled and SCALE is disabled, the format of the analog data returned will depend on the type of calibration 

implemented. If the calibration factors are stored on the device and applied to the data by the application software, the data 

will be floating point values, not integer values, and may exceed the theoretical limits and include negative values and values 

above 2 res olution -1. 

• SCALE=ENABLE 

When SCALE is enabled, scaled floating point values are returned. The limits of the data will depend on the implementation of 

calibration, as described above. Data range limits may be a small percentage less than or greater than the full scale range 

selected for devices for which the calibration factors are stored on the device and applied to the data by the application 

software. 

Page 26 of 43

AITRIG 

Sets and gets analog input trigger property values. 

Properties 

TYPE, REARM 





TYPE 


"AITRIG:TYPE=value" "AITRIG:TYPE" Sets the edge trigger type. 

value = EDGE/RISING or EDGE/FALLING 

Example: "AITRIG:TYPE=EDGE/RISING" 

"?AITRIG:TYPE" "AITRIG:TYPE=value" Returns the edge trigger type. 

value = EDGE/RISING or EDGE/FALLING 

REARM 


"AITRIG:REARM=value" "AITRIG:REARM" Sets the state of the retrigger mode. 


Example: "AITRIG:REARM=ENABLE" 

"?AITRIG:REARM" "AITRIG:REARM=value" Returns the state of the retrigger mode. 


Note 

• When running the DAQFlex test application, AITRIG messages are listed on the AISCAN tab. 

Page 27 of 43

AO 

Sets and gets property values for analog output channels. 

Properties 

VALUE, SCALE 






"?AO" "AO=value" Returns the number of analog output channels 

on the device. 

value = number of D/A channels on the device 

VALUE 


"AO{ch}:VALUE=value" "AO{ch}:VALUE" Sets the value of a D/A channel. 

ch = D/A channel number 

value = D/A value 

Example: "AO{0}:VALUE=4095" 

SCALE 1 


"AO:SCALE=value" "AO:SCALE" Enables or disables scaling of all D/A channels. 


Example: "AO:SCALE=ENABLE" 

"?AO:SCALE" "AO:SCALE=value" Returns a value indicating whether scaling will 

be applied to the D/A channels. 



Page 28 of 43

CTR 

Sets and gets property values for counter channels. 

Properties 

VALUE, START, STOP 






"?CTR" "CTR=value" Returns the number of counter channels on the 

device. 

value = number of counter channels 

VALUE 


"CTR{ch}:VALUE=value" "CTR{ch}:VALUE" Loads the specified counter with the specified 

value. 

ch = counter number 

value = counter value 

Example: "CTR{0}:VALUE=0" 

"?CTR{ch}:VALUE" "CTR{ch}:VALUE=value" Returns the value of the specified counter. 


value = counter value 

Example: "?CTR{0}:VALUE" 

START 


"CTR{ch}:START" "CTR{ch}:START" Starts the specified counter channel. 


Example: "CTR{0}:START" 

STOP 


"CTR{ch}:STOP" "CTR{ch}:STOP" Stops the specified counter channel. 


Example: "CTR{0}:STOP" 

Page 29 of 43

DIO 

Sets and gets property values for digital I/O channels. 

Properties 

DIR, VALUE 






"?DIO" "DIO=value" Returns the number of digital ports on the 

device. 

value = number of digital ports 

"?DIO{bit}" "DIO{bit}=value" Returns the number of bits in the port. 

value = number of bits in the port 

Example: "?DIO{0}" 

DIR 


"DIO{port}:DIR=value" "DIO{port}:DIR" Sets the specified port for input or output. 

port = port number 

value = IN or OUT 

Example: "DIO{0}:DIR=IN" 

• If DIR is not specified, the devise's default power up value is used. 

"?DIO{port}:DIR" "DIO{port}:DIR=value" Returns the direction of the specified port. 


• If bits are not individually configurable, the value returned will be either "IN" or "OUT." 

value = "IN", "OUT", or a number between 0 

and 2 n -1, where n is the number of bits in the 

port. 

• If each bit is individually configurable, value is a bit mask, in which a 1 indicates that the bit is configured for input, and 

a 0 indicates that the bit is configured for output. 

"DIO{port/bit}:DIR=value" "DIO{port/bit}:DIR" Sets the specified bit for input or output. 


bit = bit number 


Example: "DIO{0/1}:DIR=IN" 

• If DIR is not specified, the device's default power up value is used. 

"?DIO{port/bit}:DIR" "DIO{port/bit}:DIR=value" Returns the direction of the specified bit. 

Page 30 of 43




Example: "?DIO{0/1}:DIR" 

VALUE 


"DIO{port}:VALUE=value" "DIO{port}:VALUE" Sets the value of the specified port. 


value = value of the port 

Example: "DIO{0}:VALUE=128" 

"?DIO{port}:VALUE" "DIO{port}:VALUE=value" Returns the value of the specified port. 


value = value of the port 

Example: "?DIO{0}:VALUE" 

"DIO{port/bit}:VALUE=value" "DIO{port/bit}:VALUE" Sets the value of the specified bit. 



value = value of the bit (0 or 1) 

Example: "DIO{0/1}:VALUE=1" 

"?DIO{port/bit}:VALUE" "DIO{port/bit}:VALUE=value" Returns the value of the specified bit. 



value = value of the bit (0 or 1) 

Example: "?DIO{0/1}:VALUE" 

Page 31 of 43

Note: Click Send Message after changing the type of data to return. 

API message reference 

Click on a component link below to go the text messages, device responses, and property values supported by each DAQ component. 

AI 

AISCAN 

AITRIG 

DIO 

CTR 

DEV 

AO 

Page 34 of 43

DAQFlex Firmware Architecture 

This document contains the specifications for the interface between the DAQFlex Software API and the DAQFlex firmware that is 

required to create Message-Based DAQ (MBD) applications. 

The DAQFlex firmware uses a String Message Based Interface (SMBI) to communicate with DAQFlex Series hardware. Refer to the 

API message reference for information about the DAQ components and string messages supported by the DAQFlex API. Refer to the 

Hardware Reference section for information on the commands and property values that are supported by DAQFlex Series devices. 

SMBI data types 

Special formatting characters are retuned with RAW data (except streaming data from bulk transfers) to indicate the following data 

types: 

• char[64]: String data in a character array 

• uint8: unsigned 8-bit value 



• float32: float 32-bit value 

Communication mechanism 

The device enumerates as a USB device using an MCC driver. 

Control transfers 

• Control transfers to endpoint 0 are used to communicate with the device. 

• The control transfer maximum buffer size is 64 bytes. 

• The control transfers are vendor transfers. 

• The command code is in the bRequest field. 

¡ SMBI uses the 0x80 data type for strings, and the 0x81 data type for RAW data, when supported. 

• Parameters passed for OUT control transfers are sent during the data stage. 

• The SMBI data stage will return RAW data, LSB first. 

The DEV component message "DEV:DATATYPE=ENABLED" specifies whether raw data is enabled or disabled for returned data. 

When using "DEV:DATATYPE=ENABLED" the first byte indicates the data type returned. Refer to the Notes below for more 

information. 

• The amount of data being transferred must be specified in the wLength field. 

SMBI control messages 

• Invalid OUT messages have a STALL response, and the IN response is "INVALID", RAW return is a 0 length data packet. 

• Default return for an IN request before an OUT results in a return message of "NO COMPONENT SET" 

• Valid messages have an ACK response. 

A valid response to an IN request is in the form of a string. RAW data is only returned for supported messages. 

• A RAW data return for an invalid message is a 0 length packet, unless "DEV:DATATYPE=ENABLE" where it will return a 1 byte 

packet with 0xFF as the value indicating an error/invalid. 

Miscellaneous 

• Bulk transfers from endpoint 1 IN are used for analog input scans. 

Data is in RAW format and "DEV:DATATYPE" has no impact on the data. 

Note:Refer to device-specific information to determine whether bulk transfer components are supported. 

• Multi-byte data, for example integers, are sent LSB first. 

Page 35 of 43

Programming and developing applications 

You can access DAQFlex series hardware functions using either the DAQFlex software API library or the DAQFlex firmware 

architecture. 

• The DAQFlex software API is an open source library that implements a simple message-based protocol consisting of textbased 

commands, or messages. 

The software API operates with standard drivers for Windows or Linux. 

Refer to the Software API topics in the DAQFlex Help file for more information on using the DAQFlex software API. 

• The DAQFlex firmware architecture uses a String Message Based Interface (SMBI) to communicate with DAQFlex series 

hardware using a minimal number of device transactions. Communication with the device is accomplished through the USB 

driver (winusb, libusb, or other custom driver). Only experienced USB programmers should attempt to write a driver for use 

with the DAQFlex firmware. 

Refer to the Firmware Specification in the DAQFlex Help file for more information on using the DAQFlex firmware. The source 

code for the DAQFlex software API may be used as a guide for developing a driver to interface directly with the hardware. 

Getting started with the DAQFlex software API library 

Windows XP and Windows Vista: 

1. Run the DAQFlex.msi Windows installer. 

When running Windows XP, a winusb driver is automatically installed. This driver is included on Windows Vista. 

2. Run the DAQFlex test application (FlexTest.exe). This application is an interactive C# console program that demonstrates 

how to use the DAQFlex software API. 

Additionally, you can build and run the C# or VB .NET example programs included in the installation using ExampleBuilder or 

Visual Studio (version 2005 or greater). 

3. Review the DAQFlex Help file for the functions supported by DAQFlex series hardware. 

Linux: 

1. Using your Software/Package manager, verify that the Mono framework (version 2.4 or later) and the libusb user-mode 

driver are installed on your Linux system. 

If these versions aren't listed, information on installing, updating, or adding software repositories to your Software/Package 

manager can be found at the following links. Click here to go to the Mono web site. Click here to go to the libusb web site. 

2. As a root user, create a symbolic link to the libusb-1.0 shared object file. For example: 

¡ $ ln -s /usr/lib/libusb-1.0.so.0/usr/lib/libusb-1.0.so 

(The actual file location may vary.) 

3. Extract the files from the DAQFlex-1.3.tar.gz archive file from the DAQFlex software CD using an archive manager. 

4. In a terminal window, set the current directory to DAQFlex/Source/DAQFlexAPI. 

5. As a root user, run the following commands: 

¡ $ make 

¡ $ make install 

6. Restart the system. 

7. In a terminal window, set the current directory to DAQFlex/Source/DAQFlexTest. 

8. As a root user, run the following commands: 

¡ $ make 

¡ $ make install 

9. From a terminal window, run the FlexTest application using the following command: 

¡ $ flextest 

This application is an interactive C# console program that demonstrates how to create an application using the DAQFlex 

software API. Additionally, you can build and run the C# example programs included in the installation using MonoDevelop or 

the Mono command line interpreter. 

10. Review the DAQFlex Help.pdf file for the functions supported by DAQFLex series hardware. 

Page 42 of 43

Using the DAQFlex firmware architecture 

• Communicate with DAQFlex series hardware through the USB driver installed on your system (winusb, libusb, or other custom 

driver). 

Only experienced USB programmers should attempt to write a driver for use with the DAQFlex firmware. Experience with 

CONTROL transfers for asynchronous communications, and BULK transfers for synchronous communications is recommended. 

• Refer to the Windows driver (winusb) or the Linux driver (libusb) for an example of how to communicate with DAQFlex series 

hardware. 

• Refer to the Firmware Specification in the DAQFlex Help file for more information on using the string-based messages, transfer 

methods, and commands that are supported by the DAQFlex firmware. 

Page 43 of 43

Introducing Message-Based DAQ

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