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CEBO-LC at a glance CEBO-LC is a universal measurement and automation device. It has a plug-and-play USB interface which is isolated to prevent mutual interference between the computer and all the many things you want to connect to. Its electronics is capsuled in a rugged aluminum housing, which has rubber fittings for a secure grip. Connecting sensors and actuators can be achieved easily using the built-in screw terminals. Custom extensions can simply be plugged in to its extension DB25 connector.
Features Analog Inputs • • • • • • 14 Single-Ended or 7 Differential or any combination 16 bit resolution Software programmable gains: x1, x10, x100, x1000 Analog input ranges: 10V, 1V, 100mV, 10mV Instrumentation amplifier inputs SAR 65.000 - 85.
• Fullspeed (12 Mbit) • Isolated to improve measurement performance and protect Host computer • High retention USB connector to prevent unintented disconnection Supported Operating Systems • • • • Microsoft Windows (XP, Vista, 7, 8) (32 + 64 bit, Windows XP 32 bit only) Mac OS X, 10.6 or higher Linux (PC/Desktop), tested on Ubuntu 12.04 LTS (32 + 64 bit) Linux on Raspberry Pi (Wheezy) Supported Programming Languages/Interfaces • • • • • • C++ Java .
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CEBO-LC block diagram Figure: simplified block diagram Specification - General Parameter Condition Min Typical Max Units Dimensions (BxWxH) 75x113x36 mm Operating Temperature Range 23 70 °C 7/63
Screw terminal A selection of CEBO-LC Input/Output signals is available on industry standard 5mm screw terminals: Position of the terminals Terminal pin assignment Signal GND(1) AO-1 GND(1) AO-0 GND(1) AI-7 AI-6 Desription Analog Output 1 Analog Output 0 Analog Input 7 Analog Input 6 GND(1) Signal 5V(2) 200µA 10µA GND(1) CNT TRG GND(1) IO-7 AI-5 Analog Input 5 IO-6 AI-4 Analog Input 4 IO-5 Description Power Output Fixed Current Output Fixed Current Output Counter Input Trigger Input/Output Digi
GND(1) IO-4 AI-3 Analog Input 3 GND(1) AI-2 Analog Input 2 IO-3 GND(1) IO-2 AI-1 Analog Input 1 IO-1 AI-0 Analog Input 0 IO-0 Digital Input/Output 4 (Port 0, IO 4) Digital Input/Output 3 (Port 0, IO 3) Digital Input/Output 2 (Port 0, IO 2) Digital Input/Output 1 (Port 0, IO 1) Digital Input/Output 0 (Port 0, IO 0) 1. Screw terminals labeled GND are internally connected. 2. 5V Power Outputs are internally connected. A total of 100mA can be sourced.
Expansion Connector (DB25) Additional to the industry standard 5mm screw terminals, CEBO-LC comes with a 25pin D-SUB jack of female type.
Protective circuit of Digital I/O All Digital I/O signals on DB25 connector are short-circuit proof* and protected against temporary overvoltage. * Single I/O only. Total current should be limited to less than 25 mA. If a Digital IO is used as output to drive a Led, no additional series resistor is needed. The internal protection resistor will act as a current limiter. Example: Output Voltage when "high": 3.3V Typical forward voltage of a red Led: 1.8V (2.1V typ. for green Led) Current flow: (3.3V - 1.
USB Interface CEBO-LC is a full-speed USB 2.0 device. USB connection provides communication and power. CEBO-LC GND signal is isolated from USB/PC ground. Hence, mutual interference between host system and CEBO LC I/O signals is avoided. In other words: The CEBO-LC signals labeled GND are not connected to the host computer chassis or the host computer GND. This is a big advantage when precise and noise-free measurements are desired.
Power and status Leds CEBO-LC comes with two status LEDs. A yellow LED indicates USB connection and traffic while a green LED indicates power status or helps identifying a special CEBO-LC device optically. Green Led Primarily the green LED signals power supply connection status. If CEBO-LC is powered (i.e.
host or to an USB-Hub) the LED will turn on. Additionaly, the green LED can be switched off and on via software command. This way, when more than one device is used at a single host system, a special device can be identified optically by setting / resetting the LED. Yellow Led The yellow LED signals USB connection status and traffic. Default status after successfully establishing the USB link is on. With every USB transfer a short blink is initiated.
Analog Inputs Features: • • • • • • • 8 Single-Ended (AI-0 to AI-7) or 4 Differential on screw terminals 6 Single-Ended (AI-8 to AI-13) or 3 Differential on expansion connector DB25 16 bit resolution Software programmable gains: x1, x10, x100, x1000 Analog input ranges: 10V, 1V, 100mV, 10mV Instrumentation amplifier inputs SAR 65.000 - 85.
Vcm = (Vpos + Vneg) / 2 Vin = Vpos - Vneg Vpos = even channel of a differential pair Vneg = odd channel of a differential pair If you measure in singel-ended the odd channel is switched to ground. The limitation results from the amplifier circuit and its supply voltage and the ADC.
Example: You have two voltages (5V & 11V) relating to mass. Vin = 6V & Vcm= 8V This point is in no figure inside the hexagon, so you get no valid reading. Overvoltage protection CEBO-LC Analog Inputs are rated for 10V with respect to GND. Keep voltages on any Analog Input within 12,3V to guarantee valid readings on adjacent channels. To limit current flow in case of overvoltage an internal series resistor is added at all input channels.
prevent CEBO-LC from damage. This is also true if CEBO-LC is unpowered. Settling time In general, settling time is the time needed for the analog signal to reach a stable state at the ADC input after a step change occurred. With CEBO-LC such a step change occurs every time when input multiplexers change from one channel to another. Therefore this time is called interchannel delay time. With increasing gain settings a higher interchannel delay time may be required.
Use equations (1) and (2) to determine signal-to-noise ratio (SNR) and corresponding effective number of bits (ENOB). Equation (1) SNR|dB = 20 * log(noise / full-scale input) Equation (2) ENOB|BIT = (SNR|dB - 1,76dB) / 6,02dB Equation (3) gives a representation of noise in counts. All counts data stated in the table above are 24 bit aligned values. Equation (3) Noise|counts = 2^(24 - ENOB) To calculate a corresponding 16 bit value, counts data needs to be divided by 2^8.
also true if CEBO LC is unpowered. 4. Keep source impedance below given maximum value to ensure proper readings with default settling times. For greater source impedances You may be required to increase settling times. 5. These values were calculated as follows: ftotal = fmeasure + fcalibration device (max) fmeasure=(xd-xr) / xr f: relative error xr: value from calibration device xd: mean of n measurements from "Device Under Test" n=1000/1000/500/100 at range 10V / 1V / 100mV / 10mV 6.
Power on behavior When connecting CEBO-LC to a host system, a positive voltage might occur on analog outputs. Pulse length typically is about 6ms, peak voltage is about 1,5V. Maximum short-circuit current during this period is about 20mA. Please make sure that connected equipment is not negatively affected by this. The same behavior is true when updating CEBO-LC firmware. Please remove all connections prior to initating firmware update process with CeboLab.
Specifications - Digital Input Parameter Low Level Input Voltage High Level Input Voltage Maximum Input Voltage @Screw terminal(2)(3) @DB25 connector(2)(3) Min Typical Max Units -0,3 0,8 volts 2 5,8 volts -10 -6 10 6 volts volts Specifications - Digital Output Parameter Output Low Voltage @Screw terminal(3) @DB25 connector(3) @DB25 connector(3) Output High Voltage @Screw terminal(3) @DB25 connector(3) @DB25 connector(3) Short Circut Current (1) @Screw terminal(3) @DB25 connector(3) Total Current (1) Out
Trigger CEBO-LC has one Trigger Input/Output which is located at the TRG terminal. With firmware releases 1.
trigger is available for Multi Frame DAQ modes only. With the trigger signal, you can use an external event to start data acquisition or you can synchronize multiple CEBO-LC devices. After startup TRG is configured as input signal, but inactive. To use TRG as a trigger, the corresponding peripheral needs to be enabled first. This is done by software calls (API). An example about using TRG terminal as Trigger Input/Output is provided in Programming Reference => C++ => Trigger.
Alternating Mode In alternating mode, every acquisition of a frame toggles the level of the TRG output signal. Consequently, the resulting signal is a square wave with 50% duty cycle and half the frequency of the data acquisition frame rate. Pulse Mode In Pulse Mode every trigger event initiates a pulse of several 100ns on TRG terminal. In this mode TRG signal rate equals the frame rate used for data acquisition, but duty cycle depends on frame rate and will be less than 50%.
With every frame start, the master will toggle the level of the TRG signal, tripping a trigger on the slave devices. An example how to accomplish master/slave configurations for CEBO-LC is provided in Programming Reference => C++ => Trigger.
Counter CEBO-LC has an external counter input. It is located at the screw terminal labeled CNT.
On every rising edge on CNT, a 32 bit register is incremented. This counter requires the firmware to jump to a small interrupt service routine on each rising edge. Therefore maximum edge rate without missing counts depends on available processing resources. When the CNT counter is used exclusively, maximum input edge rate will be in the range of t.b.d. Samples/s. With Multi Frame DAQ enabled at the same time, maximum input edge rate will be less.
Temperature Sensor Inside the CEBO-LC device, the IC temperature sensor ADT7410 from Analog Devices is used to provide 0,5C accurate, 16 bit digital data. Reading the temperature is initiated by an API (software) call. A 16 bit value is returned immediately. Temperature data is not available while streaming. See chapter Programming Reference => C++ => Info for further details on how to access temperature data.
Constant-current sources CEBO-LC has two accurate built-in current sources (200A / 10A). Both are available on screw terminals. The exact values of the Fixed Current Outputs are measured during factory calibration process and stored in flash. You can find more information on how to access calibration data for the Fixed Currend Outputs in chapter Programming References => C++ => Info.
R = Voltage drop / Fixed Current Output = U / I Resistive sensors are very common to measure various physical quantities. With the help of a temperature-dependent resistor (PTC, NTC), a temperature can be measured indirectly by measuring the voltage drop across the resistor. The constant current sources can output a maximum voltage of about 3 Volt. This puts a limit to the usable measurement range. For the 200A source, it is about 15 kOhm (= 3 Volt / 200A).
Parameter Absolute Accuracy(1) Parameter Absolute Accuracy(1) Parameter Typical Voltage Output Voltage Accuracy Condition ~25°C; RSpecifications Constant Current Source 10µA Min Typical Max Units Condition Min ~25°C; R(1) Compared to calibration data stored in flash.5 Volt power supply outputCEBO LC has two 5V power supply outputs. You can use them to supply sensors, signal conditioners or any other circuit to save an additional battery or wall-plug.
Load Voltage Regulation(10% to 100% full load) Output Ripple and Noise Maximum Current (1) 15 -40°C -20°C 0°C 23°C 40°C 50°C 50 mV 140 120 110 100 80 70 mA mA mA mA mA mA (1) A resettable 100mA fuse prevents overcurrent on 5V Power Outputs.
CEBO-LC/OEM CEBO-LC is also available as "OEM-version" without the enclosure and without screw terminals. The screw-terminal signals are on a 2x20 pin standard 0,1" (2,54 mm) header instead. Use the OEM version to embed CEBO-LC functionality into your machines or devices. There is a minimum order quantity of 10 pieces.
OEM Connector Pin 1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 Signal GND(1) 10µA GND(1) TRG IO-6 GND(1) IO-3 IO-1 GND(1) AO-1 AO-0 AI-6 AI-4 GND(1) AI-2 AI-0 GND(1) VCC Description Pin 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 constant current output Trigger Input/Output Digital Input/Output 6 Digital Input/Output 3 Digital Input/Output 1 Analog Output 1 Analog Output 0 Analog input 6 Analog input 4 Analog input 2 Analog input 0 +12V 35/63 Signal 5V(2) 200µA CNT IO-7 IO-5 IO-4 IO-2 IO-0 G
37 39 GND(1) 38 P-LED(3) Power supply status and indicator LED 40 T-LED(3) USB status and traffic LED GND(1) 1. GND pins are internally connected. 2. 5V Power Outputs are internally connected. A total of 100mA can be sourced. 3. T-LED and P-LED are general purpose digital I/Os directly connected to the microcontroller. With normal firmware, these are used to drive status LEDs on the IO-Board through a series resitor located on the IO-Board.
Data acquisition The process of measuring data is called "Data acquisition". It is abbreviated DAQ. There are several ways to collect data with the CEBO-LC. We call them "DAQ modes". In this section, you will learn the basics of data acquisition with CEBO-LC.
Data acquisition modes Some measurement problems require more effort than reading one single input. Depending on the circumstances, a fixed number of measurements with well defined timing or an endless stream of measurements is desired. Sometimes, data acquisition should take place only when there is a trigger event (i.e. a external digital signal switches from low to high). Software timed - one single frame Capture and return one frame. The time when the frame is captured is not exactly defined.
Capture and return a fixed number of frames. The frame acquisition timing is generated by an internal hardware timer of the CEBO-LC. Frame data is stored in an internal buffer of the CEBO-LC before it is sent to the host. When external trigger is enabled, an edge on the TRG input is required to start capturing. This acquisition mode allows it, to capture data at a higher rate than in continuous mode under some circumstances (i.e. slow PC or heavy loaded CPU).
Frames CEBO-LC has various sources and sinks of data. Besides the analog inputs and outputs there are digital signals and counter values. One way to access them individually, would be to assign a unique address to each. Then, communication between the host and CEBO-LC would have some significant overhead to transmit and decode address data. This is why data flow to and from CEBO-LC is organized in blocks of data. They have known sizes and structures and are called "frames".
DAQ Timing Data acquisition of all channels takes place sequentially in a fixed order. The settling time after switching channels can be adjusted. It is called "Interchannel Delay". The shorter the interchannel delay is, the more frames per second you can get - but with less accuracy. Input Frame Setting up an input frame is a two step process. First, build a list of inputs that should be measured. This can be any analog input (single ended and/or differential), digital port, counter or trigger.
Interchannel delay In general, settling time defines the time needed for an analog signal to reach a stable state after a step change occured. With CEBO-LC such step changes occur, whenever a input multiplexer switches from one channel to another. To reduce impacts on measurement accuracy when switching between different analog input channels, a minimum dead time needs to be waited between subsequent measurements. This time is called the interchannel delay.
Single Value IO Single value I/O is the most basic form to sample an input or modify an output. The call is synchronous, so invoking a method processes the request always immediately, which means: • In case of sampling: The result of the called method is the sampled value, the method call lasts as long as sampling and data transmission from device to host is active. • In case of modify: The method call sends the value to the peripheral directly and returns*.
Intention The idea behind this feature is that handling multiple inputs and outputs concurrently has some benefits: • Sampling order and input to input sample distance of a selected group of inputs is always constant. • Data transfer between host and device can be optimized to a maximum. • Very easy handling when working with more than one input or output. Single InputFrame Procedure Use single frame reading if you want to read more than one input directly. First, specify the inputs to read.
Multi Frame DAQ The principles and mechanics of the previous topic are the base to understand the description in this section. Multi frame DAQ is a configurable method to sample a set of inputs in either a static frequency or using external events cyclically. Captured frames are stored in a device site buffer which can be read out from host side. Methods There are different multi DAQ methods: The main difference is the event to capture the individual frames.
8xSingleEnded 9xSingleEnded 10xSingleEnded 11xSingleEnded 12xSingleEnded 13xSingleEnded 14xSingleEnded(all) 1xDigitalPort 2xDigitalPort 3xDigitalPort 1xAnalog & all digital all (1) 10.000 9.000 8.500 7.500 7.000 6.500 6.000 90.000 71.000 41.000 41.000 4.
Digital Ports Single IO signals are grouped in digital ports. To define a frame, add whole ports, not single signals. You can individually define the direction of every signal. As default, all I/O signals are inputs.
Calibration CEBO devices come factory calibrated. All corrective calculations are performed by the API internally. This includes the setting of analog output voltages and measurement of analog inputs. The exact value of both fixed current sources is measured and stored in the device's flash memory during calibration.
Firmware-Update The firmware can be updated using CeboLab. How you can patch a device is described in detail here. Firmwares can be found on our download site.
Application Software The generic Software CEBOLAB and the APIs for various languages are common for all CEBO devices. There are two applications specially made for CEBO-LC. They are Executables (*.exe) for Windows operating systems (sorry no Mac or Linux version). Instrument-panel Data-recording CEBO-LC Control and measurement software With these new applications, the CEBO-LC measurement laboratory is now easier to use.
CEBO-LC Millivoltmeter and CEBO-LC Microvoltmeter This two applications set the CEBO-LC analog inputs to differential mode. To get stable readings the inputs are sampled multiple times. The mean value of the measurements is calculated and displayed. CEBO-LC Millivoltmeter The CEBO-LC Millivoltmeter has 7 differential inputs. The measurement range is 1 Volt.
The CEBO-LC Microvoltmeter has 7 differential inputs. The measurement range is 10 mV.
CEBO-LC Frontpanel This application displays 14 single-ended analog inputs, the actual counter value and 12 digital I/Os. The range of each analog input is selectable individually. 8 digital I/Os are configured as outputs. Their state (high/low) is controlled by switches. Two sliders control the voltage on the two analog outputs. The range is -10V to +10V.
CEBO-LC Datalogger The CEBO-LC Datalogger captures the voltage levels on all 14 analog inputs, the counter value and the state of all 20 digital inputs. The information is saved in a table together with the current date and time. Capturing is triggered by clicking on a button, by a timer or by an edge on the external trigger-input "TRG". Captured data can be saved in a file for further processing with Excel, Word or other external programs.
Labview - Demo1 This is a small tool and LabView-Demo for • measuring voltage (scew terminal only) º SingleEnded º Differential • voltage output • controlling the digital IO (scew terminal only) • setting the indicator LED Measure At the "Measure"-tab you can • • • • • enable/disable the analog inputs (SingleEnded/Differential) change the range of that channels set the analog outputs define the digital pins as output or input set/clear the digital outputs 55/63
Connect/Disconnect The "Connect/Disconnect"-tab shows you: • API version whitch is used • USB Base Version If you click at the "Enumerate"-button, you see a list and the number of all Cebo devices you can connect. To connect a device you must select it (beside the "Connct"-button) and click the "Connct"-button.
LabView - Demo 2 This is a small tool/LabView Demo for • measuring analog inputs (screw terminal only) in MultiFrame mode • exporting the measurments to a file • setting analog outputs Measure At the "Measure"-Tab you can • • • • • • enable/disable the analog channels select the range select frameRate select if the measure is external started select frameCount set the analog output When the measurement is finished a dialog appears which asks you to enter a file name.
This file is text based with the extention ".lvm" and a tabulator devider. You can open it with a standard text editor, MS Excel, Open Office Calc or with a compareable program. Connect/Disconnect The "Connect/Disconnect"-tab shows you: • API version whitch is used • USB Base Version If you click at the "Enumerate"-button, you see a list and the number of all Cebo devices you can connect. To connect a device you must select it (beside the "Connct"-button) and click the "Connct"-button.
Specification - General Parameter Condition Min Typical Max Units Dimensions (BxWxH) 75x113x36 mm Operating Temperature Range 23 70 °C Specifications - Analog Input Parameter Typical Input Range (1) Max AI Voltage to GND (2) Max AI Voltage to GND (3) Input Bias Current (4) Input Impedance (4) Source Impedance (4) Integral Linearity Error Condition Gain=1 Valid Readings No Damage Min Typical Max Units -10,5 10,09 volts -12,3 12,3 volts -20 20 volts 5 30 nA 1 G© 1 k© Gain=1, 10, 100 t.b.d t.b.
to GND and the cross talk was measured at all ranges. No other channels was measured. Specification - Analog Outputs Parameter Nominal Output Range Condition No Load @±2,5mA Min Typical Max -10 10 -9,875 9,875 Resolution 12 Absolute Accuracy 5% to 95% FS ±0,1 Integral Linearity Error ±4 Differential Linearity Error ±2 Error Due To Loading @ 100 µA 0,16 @ 1 mA 0,6 Souce Impedance 50 Short Circuit Current (1) Max to GND 45 Time Constant t.b.d. 1. Continuous short circuit will not cause damage.
Total Current (1) Output Impedance @Screw terminal(3) @DB25 connector(3) 25 507 183 mA ? ? 1. Short-circuit proof single I/O only. Total current should be limited to less than 25 mA. 2. Keep voltages on Digital I/O below Maximum Input Voltage to prevent CEBO-LC from damage. This is also true, if CEBO-LC is unpowered. 3. Protective circuit of Digital I/O on the screw terminals differs from that on the Sub-D jack.
Input Total Edge Rate (2) Without reading (3) Continuously polling Counter value Mutli Frame DAQ @ 1 kHz (4) Mutli Frame DAQ @ 25 kHz (4) 300.000 35.000 25.000 5.000 edges/s edges/s edges/s edges/s 1. Keep voltages on Trigger I/O below Maximum Input Voltage to prevent CEBO-LC from damage. This is also true, if CEBO-LC is unpowered. 2. Keep the total number of edges below the Max limit, to avoid missing edges. 3. Counter value is only checked, after counting events have been disabled. 4.
50°C 70 (1) A resettable 100mA fuse prevents overcurrent on 5V Power Outputs.