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USB-1408FS-Plus Analog and Digital I/O User's Guide Document Revision 4a November 2014 © Copyright 2014 Your new Measurement Computing product comes with a fantastic extra — Management committed to your satisfaction! Thank you for choosing a Measurement Computing product—and congratulations! You own the finest, and you can now enjoy the protection of the most comprehensive warranties and unmatched phone tech support. It’s the embodiment of our mission:  To provide data acquisition hardware and software that will save time and save money. Simple installations minimize the time between setting up your system and actually making measurements. We offer quick and simple access to outstanding live FREE technical support to help integrate MCC products into a DAQ system. Limited Lifetime Warranty: Most MCC products are covered by a limited lifetime warranty against defects in materials or workmanship for the life of the product, to the original purchaser, unless otherwise noted. 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HM USB-1408FS-Plus.docx 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 ......................................................................................................................... 5 Where to find more information ......................................................................................................................... 5 Chapter 1 Introducing the USB-1408FS-Plus ....................................................................................................... 6 Functional block diagram ................................................................................................................................... 6 Chapter 2 Installing the USB-1408FS-Plus ........................................................................................................... 7 What comes with your shipment? ....................................................................................................................... 7 Hardware .......................................................................................................................................................................... 7 Software ............................................................................................................................................................................ 7 Documentation .................................................................................................................................................................. 7 Unpacking........................................................................................................................................................... 7 Installing the software ........................................................................................................................................ 7 Installing the hardware ....................................................................................................................................... 7 Calibrating the hardware..................................................................................................................................... 8 Chapter 3 Functional Details ................................................................................................................................. 9 Analog input acquisition modes ......................................................................................................................... 9 Software paced .................................................................................................................................................................. 9 Hardware paced ................................................................................................................................................................ 9 External components ........................................................................................................................................ 10 USB connector .................................................................................................................................................................10 LED .................................................................................................................................................................................10 Screw terminals................................................................................................................................................................10 Signal connections ............................................................................................................................................ 12 Analog input ....................................................................................................................................................................12 Analog output ..................................................................................................................................................................14 Digital I/O ........................................................................................................................................................................15 Counter input ...................................................................................................................................................................16 Trigger input ....................................................................................................................................................................16 SYNC I/O ........................................................................................................................................................................16 Power output ....................................................................................................................................................................16 Ground .............................................................................................................................................................................16 Accuracy ........................................................................................................................................................... 16 Synchronized operations ................................................................................................................................... 19 Power ................................................................................................................................................................ 19 Mechanical drawings ........................................................................................................................................ 20 Chapter 4 Specifications ......................................................................................................................................21 Analog input ..................................................................................................................................................... 21 Accuracy ..........................................................................................................................................................................22 Noise performance ...........................................................................................................................................................22 Analog output ................................................................................................................................................... 22 Digital input/output........................................................................................................................................... 23 External trigger ................................................................................................................................................. 24 External clock input/output............................................................................................................................... 24 3 USB-1408FS-Plus User's Guide Counter ............................................................................................................................................................. 25 Memory ............................................................................................................................................................ 25 Microcontroller ................................................................................................................................................. 25 Power ................................................................................................................................................................ 25 General ............................................................................................................................................................. 26 Environmental .................................................................................................................................................. 26 Mechanical ....................................................................................................................................................... 26 Screw terminal connector ................................................................................................................................. 26 Differential mode pinout ..................................................................................................................................................27 Single-ended mode pinout ...............................................................................................................................................27 Declaration of Conformity ..................................................................................................................28 4 Preface About this User's Guide What you will learn from this user's guide This user's guide describes the Measurement Computing USB-1408FS-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. bold text Bold text is used for the names of objects on a screen, such as buttons, text boxes, and check boxes. italic text Italic text is used for the names of manuals and help topic titles, and to emphasize a word or phrase. Where to find more information Additional information about USB-1408FS-Plus hardware is available on our website at www.mccdaq.com. You can also contact Measurement Computing Corporation with specific questions.     Knowledgebase: kb.mccdaq.com Tech support form: www.mccdaq.com/support/support_form.aspx Email: techsupport@mccdaq.com Phone: 508-946-5100 and follow the instructions for reaching Tech Support For international customers, contact your local distributor. Refer to the International Distributors section on our website at www.mccdaq.com/International. 5 Chapter 1 Introducing the USB-1408FS-Plus The USB-1408FS-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 13-bit single-ended inputs or four 14-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 trigger input Bidirectional terminal for external clocking or multi-unit synchronization Screw terminals for field wiring connections The device is powered by the +5 V USB supply from the computer. No external power is required. The USB-1408FS-Plus is compatible with both USB 1.1 and USB 2.0 ports. The speed of the device may be limited when using a USB 1.1 port due to the difference in transfer rates on the USB 1.1 versions of the protocol (low-speed and full-speed). Functional block diagram Device functions are illustrated in the block diagram shown here. Figure 1. USB-1408FS-Plus functional block diagram 6 Chapter 2 Installing the USB-1408FS-Plus What comes with your shipment? Verify that the following hardware components are included in the shipment. Hardware   USB-1408FS-Plus USB cable Software MCC DAQ CD Documentation   MCC DAQ Quick Start The MCC DAQ Quick Start booklet provides an overview of the MCC DAQ software you received with the device, and includes information about installing the software. Please read this booklet completely before installing any software or hardware. DAQami Quick Start The DAQami Quick Start insert provides information about the DAQami advanced data logging application, including a quick start procedure and quick reference guide. 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. Installing the software Refer to the MCC DAQ Quick Start for instructions on installing the software on the MCC DAQ CD. Refer to the device product page on the Measurement Computing website for information about the included and optional software supported by the USB-1408FS-Plus. Install the software before you install your device The driver needed to run the USB-1408FS-Plus is installed with the software. Therefore, you need to install the software package you plan to use before you install the hardware. For operation on a Windows operating system, we recommend that you run Windows Update to update your operating system with the latest USB drivers. Installing the hardware To connect the device to your system, turn on your computer and connect the USB cable to an available USB port on the computer or to an externally powered USB hub connected to the computer. Connect the other end of the USB cable to the USB connector on the device. No external power is required. When connected for the first time, a Found New Hardware dialog opens when the operating system detects the device. When the dialog box closes, the installation is complete. The LED turns on after the device is successfully installed. 7 USB-1408FS-Plus User's Guide Installing the USB-1408FS-Plus Caution! Do not disconnect any device from the USB bus while the computer is communicating with the device, or you may lose data and/or your ability to communicate with the device. If the LED turns off If the LED is on but then turns off, the computer has lost communication with the device. To restore communication, disconnect the USB cable from the computer and then reconnect it. This should restore communication, and the LED should turn on. Calibrating the hardware The Measurement Computing Manufacturing Test department performs the initial factory calibration. Return the device to Measurement Computing Corporation when calibration is required. The recommended calibration interval is one year. The USB-1408FS-Plus does not support field calibration. 8 Chapter 3 Functional Details Analog input acquisition modes The USB-1408FS-Plus can acquire analog input data in either software paced or continuous scan mode. Software paced The USB-1408FS-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. The USB-1408FS-Plus can attain throughput sample rate in software paced mode is system-dependent. Hardware paced The USB-1408FS-Plus can acquire data from up to eight channels using hardware-paced mode. The analog data is acquired and converted to digital values until you stop the scan. Data is transferred in blocks of 32 samples minimum from the device to the memory buffer on your computer. The A/D converter is paced by either an internal or external clock source. The maximum sample rate is an aggregate rate. The total sample rate for all channels cannot exceed 48 kS/s. The following table lists the sample rate when scanning from one to eight channels. Maximum per channel sample rate # channels scanned Sample rate (kS/s) 1 2 3 4 5 6 7 8 48 24 16 12 9.60 8 6.85 6 You can start a hardware-paced scan with a software command. Optionally, hardware-paced scans can be delayed by an external hardware trigger event. 9 USB-1408FS-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 +5 V power and communication. No external power supply is required. LED The following table lists the behavior of the device LED. LED state Indication Steady green Blinks continuously The device is connected to a computer or external USB hub. Data is being transferred. Screw terminals The screw terminals provide the following connections:         Eight analog input connections (CH0 IN to CH7 IN, CH0 IN HI/LO through CH3 IN HI/LO) Two analog output connections (D/A OUT 0 to D/A OUT 1) 16 digital I/O connections (PortA0 to Port A7, and Port B0 to Port B7) External trigger input (TRIG_IN) External counter input (CTR) Bidirectional terminal for external clocking or multi-unit synchronization (SYNC) Power output (+VO) Analog ground (AGND) and ground (GND) Use 16 AWG to 30 AWG wire when making connections to the screw terminals. 10 USB-1408FS-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. Differential mode pinout 11 USB-1408FS-Plus User's Guide Functional Details Signal connections Analog input You can connect up to eight analog input connections to the screw terminal containing pins 1 to 20 ( CH0 IN through CH7 IN.) You can configure the analog input channels as eight single-ended channels or four differential channels. When configured for differential mode, each analog input has 14-bit resolution. When configured for single-ended mode, each analog input has 13-bit resolution, due to restrictions imposed by the A/D converter. Single-ended configuration When configured for single-ended input mode, the input signal is referenced to signal ground (GND) and delivered through two wires:   Connect the wire carrying the signal to be measured to CH# IN. Connect the second wire to AGND. The input range for single-ended mode is ±10 V. The single-ended mode pinout is shown in Figure 3 on page 11. Differential configuration When configured for differential input mode, the input signal is measured with respect to the low input and delivered through three wires:    Connect the wire carrying the signal to be measured to CH# IN HI Connect the wire carrying the reference signal to CH# IN LO Connect the third wire to GND. The differential mode pinout is shown in Figure 4 on page 11. Note: To perform a single-ended measurement using differential channels, connect the signal to CH# IN HI and ground the associated CH# IN LO input. A low-noise precision programmable gain amplifier (PGA) is available on differential channels to provide gains of up to 20 and a dynamic range of up to 14-bits. Differential mode input voltage ranges are ±20 V, ±10 V, ±5 V, ±4 V, ±2.5 V, ±2.0 V, ±1.25 V, and ±1.0 V. In differential mode, the following two requirements must be met for linear operation:   Any analog input must remain in the −10V to +20V range with respect to ground at all times. The maximum differential voltage on any given analog input pair must remain within the selected voltage range. The input [common-mode voltage + signal] of the differential channel must be in the −10 V to +20 V range in order to yield a useful result. 12 USB-1408FS-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. Differential voltage example: common mode voltage of 0 V If you increase the common mode voltage to 11 V, the differential remains at 8 V. Although the [common-mode voltage + signal] on each input now has a range of +7 V to +15 V, both inputs still satisfy the –10 V to +20 V input requirement (see Figure 6). Figure 6. Differential voltage example: common mode voltage of 11 V If you decrease the common-mode voltage to –7 V, the differential stays at 8 V. However, the solution now violates the input range condition of –10 V to +20 V. The voltage on each analog input now swings from –3 V to –11 V. Voltages between –10 V and –3 V are resolved, but those below –10 V are clipped, as shown in Figure 7. Figure 7. Differential voltage example: common mode voltage of –7 V Since the analog inputs are restricted to a −10 V to +20 V signal swing with respect to ground, all ranges except ±20V can realize a linear output for any differential signal with zero common mode voltage and full scale signal inputs. The ±20 V range is the exception. You cannot put −20 V on CH# IN HI and 0 V on CH# IN LO, since this violates the input range criteria. 13 USB-1408FS-Plus User's Guide Functional Details The table below shows some possible inputs and the expected results. Sample inputs and differential results CH# IN HI CH# IN LO Result −20 V −15 V −10 V −10 V 0V 0V +10 V +10 V +15 V +20 V 0V +5 V 0V +10 V +10 V +20 V −10 V 0V −5 V 0 Invalid Invalid −10 V −20 V −10 V −20 V +20 V +10 V +20 V +20 V For more information on analog signal connections For more information on single-ended and differential inputs, refer to the Guide to DAQ Signal Connections (this document is available on our web site at www.mccdaq.com/signals/signals.pdf) Channel-Gain queue The channel gain queue feature allows you to set up a scan sequence with a unique per-channel gain setting and channel sequence. The settings are stored in a channel-gain queue list that is written to local memory on the device. The gain queue can contain up to eight elements in single-ended mode, and up to four elements in differential mode. The elements must be unique and listed in ascending order. An example of a four-element list is shown in the table below. Sample channel-gain queue list Element Channel Range Gain 0 1 2 3 CH0 CH1 CH2 CH3 BIP20V BIP5V BIP10V BIP2V 1 4 2 10 When a scan begins with the gain queue enabled, the device reads the first element, sets the appropriate channel number, range, and gain, and then acquires a sample. The properties of the next element are then retrieved, and another sample is acquired. This sequence continues until all elements in the gain queue have been selected. When the end of the channel list is detected, the sequence returns to the first element in the list. The sequence repeats until the specified number of samples is acquired. Carefully match the gain to the expected voltage range on the associated channel or an over range condition may occur. Although this condition does not damage the device, it does produce a useless full-scale reading, and can introduce a long recovery time due to saturation of the input channel. For more information about analog signal connections For more information about analog input connections, refer to the Guide to DAQ Signal Connections (this document is available on our web site at www.mccdaq.com/signals/signals.pdf). Analog output You can connect up to two analog output connections to D/A OUT 0 and D/A OUT 1. Each channel can be paced at rates up to 50,000 updates per second. The output range is 0 V to 5 V. 14 USB-1408FS-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. Refer to the schematic shown in Figure 8. Figure 8. Schematic showing switch detection by digital channel Port A0 If you set the switch to the +5 V input, Port A0 reads TRUE (1). When set to GND, Port A0 reads FALSE (0). Pull-up/down configuration All digital I/O lines are pulled high to USB +5 V with a 47 kΩ resistor by default. You can change the pull-up/down configuration using internal jumpers. You must remove the device housing to access the jumpers on the circuit board. Complete the following steps to set the jumper for pull-up or pull-down: 1. 2. Unplug the device from the computer. Turn the device over and rest the top of the housing on a flat, stable surface. Caution! The discharge of static electricity can damage some electronic components. Before removing the USB-1408FS from its housing, ground yourself using a wrist strap or touch the computer chassis or other grounded object to eliminate any stored static charge. 3. 4. Remove the three screws from the bottom of the device using a #1 Philips head screwdriver. Hold both the top and bottom sections together, turn the device over and rest it on the surface, then carefully remove the top section of the case to expose the circuit board. The user-configurable jumpers are labeled DIO A and DIO B. Figure 9 shows the location of each jumper on the circuit board. Figure 9. Pull-up/down jumper locations 5. Set each jumper for pull-up or pull-down, as shown in Figure 10. Use the jumper labeled DIO A to configure Port A, and DIO B to configure Port B. 15 USB-1408FS-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 DAQ Signal Connections (available on our web site at www.mccdaq.com/signals/signals.pdf). Counter input The CTR terminal is a 32-bit event counter that can accept frequency inputs up to 1 MHz. The internal counter increments when the TTL levels transition from low to high. Trigger input The TRIG_IN connection is an external trigger input that you can configure for either rising or falling edge. SYNC I/O The SYNC terminal is a bidirectional I/O signal that can be configured as an input (default) or an output.   Configure as an external clock input to pace the A/D conversions from an external source. The SYNC terminal supports TTL-level input signals of up to 48 kHz. Configure as an output to pace the conversions on a second device and acquire data from 16 channels using one clock. For more information about synchronized operations see page 19. Power output The +VO connection draws power from the USB connector on the computer. Caution! The +VO terminal is an output. Do not connect to an external power supply or you may damage the USB-1408FS-Plus and possibly the computer. Ground The analog ground (AGND) terminals provide a common ground for all analog channels. The digital ground (GND) terminals provide a common ground for the digital, trigger, counter, and sync channels and the power terminal. Accuracy The overall accuracy of any instrument is limited by the error components within the system. Resolution is often incorrectly used to quantify the performance of a measurement product. While "14-bits" or "1 part in 16384" does indicate what can be resolved, it provides little insight into the quality of an absolute measurement. Accuracy specifications describe the actual results that can be realized with a USB-1408FS-Plus. There are three types of errors which affect the accuracy of a measurement system:    offset gain nonlinearity The primary error sources in the USB-1408FS-Plus are offset and gain. Nonlinearity is small in each device, and is not significant as an error source with respect to offset and gain. 16 USB-1408FS-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 22 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 8192. Any deviation from this is an offset error. Figure 12 shows an example of a transfer function with a ±2.44 mV offset error. Offset error affects all codes equally by shifting the entire transfer function up or down along the input voltage axis. The accuracy plots in Figure 12 are drawn for clarity and are not drawn to scale. Figure 12. ADC transfer function with offset error 17 USB-1408FS-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. ADC Transfer function with gain error Figure 14 shows an example of a transfer function with a calibrated gain error of ±0.02%, or ±2 mV. This means that at full scale, neglecting the effect of offset for the moment, the measurement would be within 2 mV of the actual value. Note that gain error is expressed as a ratio. Values near ±FS are more affected from an absolute voltage standpoint than are values near mid-scale, which see little or no voltage error. Combining these two error sources in Figure 14, we have a plot of the error band of the ±10 V range. This is a graphical version of the typical accuracy specification of the product. The accuracy plots in Figure 14 are drawn for clarity and are not drawn to scale. Figure 14. Error band plot 18 USB-1408FS-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. Power Connecting the device to a computer draws