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App Notes

Software & Driver

 

5.6 - AIContinuous

After receiving a continuous AI command, the LabJack collects 4 channels at a sample rate determined by AIINT ( Analog Input Interval ) which is the interval between samples in cycles. The data is put in the buffer as it is sampled. Simultaneously, the LabJack pulls data out of the buffer and tries to send it to the host. This continues until the LabJack receives any command from the host. If a command is received the continuous operation is canceled and the command is executed normally. If the LED is enabled, it toggles every 40 samples during acquisition and is set on when stopped.

Table 5.6-1.

Command  
Byte # Description
0 Bit 7: X
  Bits 6-4: PGA for 1st Channel
  Bits 3-0: MUX command for 1st Channel.
1 Bit 7: X
  Bits 6-4: PGA for 2nd Channel
  Bits 3-0: MUX command for 2nd Channel.
2 Bit 7: X
  Bits 6-4: PGA for 3rd Channel
  Bits 3-0: MUX command for 3rd Channel.
3 Bit 7: X
  Bits 6-4: PGA for 4th Channel
  Bits 3-0: MUX command for 4th Channel.
4 Bit 7: Feature Reports
  Bit 6: Counter Read
  Bits 5-2: XXXX
  Bit 1: Update IO
  Bit 0: LED State
5 Bits 7-4: 1001 (Start Continuous)
  Bits 3-0: Bits for IO3 through IO0 States
6 AIINTMSB
7 AIINTLSB
   
   
Response  
Byte # Description
0 Bit 7-6: 11
  Bit 5: Buffer Overflow if Backlog = 11111, Checksum Error if Backlog = 0
  Bit 4: PGA Overvoltage
  Bits 3-0: Bits for IO3 through IO0 States
1 Bits 7-5: Iteration Counter
  Bits 4-0: Backlog/256
2 Bits 7-4: Most Significant Bits from 1st Channel
  Bits 3-0: Most Significant Bits from 2nd Chanel
3 Least Significant Byte from 1st Channel
4 Least Significant Byte from 2nd Channel
5 Bits 7-4: Most Significant Bits from 3rd Channel
  Bits 3-0: Most Significant Bits from 4th Chanel
6 Least Significant Byte from 3rd Channel
7 Least Significant Byte from 4th Channel
  • PGA Gain Setting – (Differential Only) 0b000 = 1, 0b001 = 2, 0b010 = 4, 0b100 = 8, 0b101 = 10, 0b110 = 16, 0b111 = 20
  • Mux Settings – 0b0000 = 0-1 (Differential), 0b0001 = 2-3 (Differential), 0b0010 = 4-5 (Differential), 0b0011 = 6-7 (Differential). Single-Ended readings = 0b1000 + AI Number.