USB-1208FS-Plus Analog and Digital I/O User's Guide Document Revision 5 October 2015 © Copyright 2015
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Table of Contents Preface About this User's Guide ....................................................................................................................... 5 What you will learn from this user's guide ......................................................................................................... 5 Conventions in this user's guide .........................................................................................................................
USB-1208FS-Plus User's Guide Microcontroller ................................................................................................................................................. 24 Power ................................................................................................................................................................ 24 General ...........................................................................................................................................
Preface About this User's Guide What you will learn from this user's guide This user's guide describes the Measurement Computing USB-1208FS-Plus data acquisition device and lists device specifications. Conventions in this user's guide For more information Text presented in a box signifies additional information and helpful hints related to the subject matter. Caution! Shaded caution statements present information to help you avoid injuring yourself and others, damaging your hardware, or losing your data.
Chapter 1 Introducing the USB-1208FS-Plus The USB-1208FS-Plus is an analog input and digital I/O data acquisition device that provides the following features: Eight analog input channels that are software configurable for either eight 11-bit single-ended inputs or four 12-bit differential inputs Two 12-bit analog output channels 16 digital I/O channels that are independently-selectable as input or output in two 8-bit ports 32-bit event counter input for counting TTL pulses External digital t
Chapter 2 Installing the USB-1208FS-Plus Unpacking As with any electronic device, you should take care while handling to avoid damage from static electricity. Before removing the device from its packaging, ground yourself using a wrist strap or by simply touching the computer chassis or other grounded object to eliminate any stored static charge. Contact us immediately if any components are missing or damaged.
Chapter 3 Functional Details Analog input acquisition modes The USB-1208FS-Plus can acquire analog input data in either software paced or hardware paced mode. Software paced The USB-1208FS-Plus acquires data one analog sample at a time using software paced mode. You initiate the A/D conversion by calling a software command. The analog value is converted to digital and returned to the computer. You can repeat this procedure until you have the total number of samples that you want.
USB-1208FS-Plus User's Guide Functional Details External components The external components – screw terminal banks, LED, and USB connector –are shown in Figure 2. 1 2 Screw terminal pins 21 to 40 LED 3 4 Screw terminal pins 1 to 20 USB connector Figure 2. External components USB connector Receives the supplied USB cable. When connected to a computer or USB hub, the cable provides power and communication. No external power supply is required.
USB-1208FS-Plus User's Guide Functional Details The single-ended mode pinout is shown in Figure 3. Figure 3. Single-ended mode pinout The differential mode pinout is shown in Figure 4. Figure 4.
USB-1208FS-Plus User's Guide Functional Details Signal connections Analog input You can connect up to eight analog input connections to the screw terminal bank containing pins 1 to 20. You can configure the analog input channels as eight single-ended channels (CH0 IN through CH7 IN) or four differential channels (CH0 IN HI/LO through CH3 IN HI/LO). When configured for differential mode, each analog input has 12-bit resolution.
USB-1208FS-Plus User's Guide Functional Details For example, you input a 4 V pp sine wave to CH# IN HI, and apply the same sine wave 180° out of phase to CH# IN LO. The common mode voltage is 0 V. The differential input voltage swings from 4 V – (–4 V) = 8 V to –4 V – (4 V) = –8V. Both inputs satisfy the –10 V to +20 V input range requirement, and the differential voltage is suited for the ±10 V input range (see Figure 5). Figure 5.
USB-1208FS-Plus User's Guide Functional Details The table below shows some possible inputs and the expected results.
USB-1208FS-Plus User's Guide Functional Details Digital I/O The device has 16 DIO channels that are configured as two 8-bit ports – Port A and Port B. Port B is high drive. You can connect up to eight DIO lines to Port A0 to Port A7 and up to eight DIO lines to Port B0 to Port B7. You can configure each port for either input or output. The digital ports are set for input when the device is powered on or reset. When configured for input, the digital I/O terminals can detect the state of any TTL-level.
USB-1208FS-Plus User's Guide Functional Details Figure 10. Pull-up/down jumper configuration 6. Replace the top section of the housing, and fasten it to the bottom section with the three screws. For more information on digital signal connections For more information on digital signal connections and digital I/O techniques, refer to the Guide to Signal Connections (available on our web site at www.mccdaq.com/pdfs/DAQ-Signal-Connections.pdf).
USB-1208FS-Plus User's Guide Functional Details Figure 11 shows an ideal, error-free transfer function. The typical calibrated accuracy is range-dependent. Refer to the "Accuracy specifications" on page 21 for more information. We use a ±10 V range here as an example of what you can expect when performing a measurement in this range. Figure 11. Ideal ADC transfer function The offset error is measured at mid-scale. Ideally, a zero volt input should produce an output code of 2048.
USB-1208FS-Plus User's Guide Functional Details Gain error is a change in the slope of the transfer function from the ideal, and is typically expressed as a percentage of full-scale. Figure 13 shows the transfer function with gain error. Gain error is easily converted to voltage by multiplying the full-scale (FS) input by the error. The accuracy plots in Figure 13 are drawn for clarity and are not drawn to scale. Figure 13.
USB-1208FS-Plus User's Guide Functional Details Synchronized operations You can connect the SYNC pin of two devices together in a master/slave configuration and acquire data from the analog inputs of both devices using one clock. When the SYNC pin is configured as an output, the internal A/D pacer clock signal is sent to the screw terminal. Output the clock signal to the SYNC pin of a second device that is configured for A/D pacer input.
USB-1208FS-Plus User's Guide Functional Details Mechanical drawings Figure 15.
Chapter 4 Specifications All specifications are subject to change without notice. Typical for 25°C unless otherwise specified. Specifications in italic text are guaranteed by design. Analog input Table 1.
USB-1208FS-Plus User's Guide Specifications Accuracy Table 2. Accuracy, differential mode Range Accuracy (LSB) ±20 V ±10 V ±5 V ±4 V ±2.5 V ±2 V ±1.25 V ±1 V 5.1 6.1 8.1 9.1 12.1 14.1 20.1 24.1 Table 3. Accuracy, single-ended mode Range Accuracy (LSB) ±10 V 4.0 Table 4. Accuracy components, differential mode – all values are (±) Range % of Reading Gain Error at FS (mV) Offset (mV) Accuracy at FS (mV) ±20 V ±10 V ±5 V ±4 V ±2.5 V ±2 V ±1.25 V ±1 V 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.
USB-1208FS-Plus User's Guide Specifications Analog output Table 8. Analog output specifications Parameter Resolution Output range Number of channels Throughput (Note 4) Power on and reset voltage Output drive Slew rate Condition Specification Software paced Hardware paced 12-bits, 1 in 4,096 0 V to 5.0 V 2 250 S/s single channel typ, PC dependent 50 kS/s max per channel Initializes to 000h code 5 mA, sourcing 0.8 V/ µs typ Each D/A OUT Note 4: Maximum throughput when scanning is machine dependent.
USB-1208FS-Plus User's Guide Specifications External trigger Table 12. Digital trigger specifications Parameter Specification Trigger source (Note 7) Trigger mode External digital; TRIG_IN terminal Edge sensitive; software-selectable for CMOS compatible rising or falling edge, high or low level. 10 µs max 1 µs min Schmitt trigger, 47 kΩ pull-down to ground 1.01 V typ 0.6 V min 1.5 V max 2.43 V typ 1.9 V min 3.1 V max 5.5 V absolute max 1.42 V typ 1.0 V min 2.0 V max –0.
USB-1208FS-Plus User's Guide Specifications Counter Table 14. Counter specifications Parameter Specification Pin name Counter type Number of channels Input type Input source Resolution Maximum input frequency High pulse width Low pulse width Schmitt trigger hysteresis CTR Event counter 1 Schmitt trigger, 47 kΩ pull-down to ground, rising edge triggered CTR screw terminal 32 bits 1 MHz 500 ns min 500 ns min 1.01 V typ 0.6 V min 1.5 V max 2.43 V typ 1.9 V min 3.1V max 5.5 V absolute max 1.42 V typ 1.
USB-1208FS-Plus User's Guide Specifications General Table 18. General specifications Parameter Specification Device type Device compatibility USB 2.0 full speed USB 1.1, USB 2.0 Environmental Table 19. Environmental specifications Parameter Specification Operating temperature range Storage temperature range Humidity 0 °C to 70 °C –40 °C to 70 °C 0% to 90% non-condensing Mechanical Table 20.
USB-1208FS-Plus User's Guide Specifications Differential mode pinout Table 22.
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