SDM-CVO4 4-Channel Current/Voltage Output Module Revision: 7/11 C o p y r i g h t © 2 0 0 1 - 2 0 1 1 C a m p b e l l S c i e n t i f i c , I n c .
Warranty and Assistance PRODUCTS MANUFACTURED BY CAMPBELL SCIENTIFIC, INC. are warranted by Campbell Scientific, Inc. (“Campbell”) to be free from defects in materials and workmanship under normal use and service for twelve (12) months from date of shipment unless otherwise specified on the corresponding Campbell invoice. Batteries, fine-wire thermocouples, desiccant, and other consumables have no warranty.
SDM-CVO4 Table of Contents PDF viewers note: These page numbers refer to the printed version of this document. Use the Adobe Acrobat® bookmarks tab for links to specific sections. 1. Introduction..................................................................1 2. Specifications ..............................................................2 2.1 General Specifications ..............................................................................2 2.2 Output Specifications..................................
SDM-CVO4 Table of Contents Tables 4-1. 4-2. 6-1. 6-2. Datalogger to SDM-CVO4 Connections ................................................ 4 Switch Position and Addresses............................................................. 10 Description of SDM Speed................................................................... 16 Description of Instruction 103..............................................................
SDM-CVO4 4-Channel Current/Voltage Output Module The SDM-CVO4 is a synchronously addressed datalogger peripheral designed to allow the datalogger to output variable voltage or current signals under program control. FIGURE 1. SDM-CVO4 (shown without mounting brackets) 1. Introduction The SDM-CVO4 expands the analog output capability of Campbell Scientific dataloggers. Each output can be set to 0-10V or 0-20mA by the datalogger.
SDM-CVO4 4-Channel Current/Voltage Output Module The SDM-CVO4 is a synchronously addressed datalogger peripheral. The datalogger’s SDM ports are used to address the SDM-CVO4 and send out data that defines the desired voltage/current output of each of the four channels. The output levels are set by four values stored in variables or successive input locations in the datalogger. A total of up to sixteen SDM-CVO4s or other SDM peripherals may be connected and addressed from the same three ‘SDM’ ports.
SDM-CVO4 4-Channel Current/Voltage Output Module Weight: 370 g EMC Status: Complies with EN55022-1:1998 and EN500821:1998 2.2 Output Specifications Voltage Mode: Current Mode: Range: 0 – 10,000 mV Resolution: 2.5 mV Maximum Output Current: 30 mA per channel. Minimum load current: 5 μA if output < 200 mV. Accuracy (+23°C): ±0.02% of set voltage + (± 2.5 mV). Accuracy (-25 to +50°C): ±0.13% of set voltage + (± 2.5 mV). Range: 0 – 20 mA Resolution: 5 μA Minimum output current (leakage): 5 μA at +50°C.
SDM-CVO4 4-Channel Current/Voltage Output Module Maximum recommended continuous operating voltage: 240 VAC RMS differential between an output and datalogger ground - providing all issues relating to local regulations for safe installation and operation are followed (see section 4.5, safety issues). 3. Power Considerations The SDM-CVO4 power requirements are large compared to most Campbell Scientific products, especially when driving significant loads.
SDM-CVO4 4-Channel Current/Voltage Output Module NOTE If the total cable length connecting SDM-CVO4s to SDM-CVO4s, other SDMs and the datalogger exceeds 6 m, the SDM baud rate may need to be reduced to ensure reliable operation. Please contact Campbell Scientific for more information. The transient protection of the SDM-CVO4 relies on a low resistance path to earth. Ensure that the ground return wire has as low a resistance as possible.
SDM-CVO4 4-Channel Current/Voltage Output Module You cannot reliably insert more than one solid-core wire into one terminal connector unless the wires are soldered or clamped together. When inserting more than one stranded wire, twist the bare ends together before insertion. 4.2 Output Device Connections For each output channel there are four terminals which are labeled Vo, Id plus ) connections per channel.
SDM-CVO4 4-Channel Current/Voltage Output Module or CVO4 Id V+ + Remote Current Input V- b) The SDM-CVO4 provides the voltage source to drive the loop. In this case the only real option is: + CVO4 Vo Remote Current Input Id – In both cases you need to consider whether the voltage supply is high enough to allow the maximum current to flow (20 mA) through all of the series resistances in the current loop. When considering this factor you need to allow terminal of the for a minimum 2.
SDM-CVO4 4-Channel Current/Voltage Output Module SDM-CVO4. Do not connect the screen at both ends of the cable as this may result in a ground loop being formed. The output circuitry of the SDM-CVO4 includes protective components to minimize the chances of damage that can be caused by transients which can be induced in the signal cable. The protection clamps the transient voltages to non-damaging levels relative to the ground terminals on each output channel.
SDM-CVO4 4-Channel Current/Voltage Output Module Select channel(s) by fitting jumper (s) between appropriate terminals. (Current mode only.) Jumper shown fitted to ‘enable’ Channel 4. Jumper shown fitted in the unconnected ‘stored’ position. FIGURE 4-3. Location of Jumpers on Circuit Board CAUTION Do not store the jumpers between any other pins in the block as this may switch the module into a factory calibration mode, which may result in abnormal operation and change of output accuracy.
SDM-CVO4 4-Channel Current/Voltage Output Module TABLE 4-2. Switch Position and Addresses Switch Setting Base 4 Address 0 1 2 3 4 5 6 7 8 9 A B C D E F 00 01 02 03 10 11 12 13 20 21 22 23 30 31 32 33 Use a screwdriver to select address FIGURE 4-4. Address Selection Switch The address switch has a hexadecimal setting position (0..F). Most datalogger instructions require you to enter the address as a base 4 number. Please see your datalogger manual for more details of the convention required. 4.
SDM-CVO4 4-Channel Current/Voltage Output Module Where the SDM-CVO4 is going to be used in applications where the potential difference between the datalogger and the output terminals exceeds 50 V RMS AC, 74 VDC then careful consideration has to be taken to ensure safe operation and compliance with local safety regulations. For such applications Campbell Scientific does not supply the device as a stand-alone device which will meet all safety requirements.
SDM-CVO4 4-Channel Current/Voltage Output Module is rated to withstand a 2700V, 2 second flash test, but will fail if exposed to voltages in excess of 240 V RMS for long periods. b) To provide protection from transients and static for this capacitor and the opto-isolation component that bridges the barrier, there is a spark gap across the barrier that has a 2500 VDC nominal breakdown voltage.
SDM-CVO4 4-Channel Current/Voltage Output Module problem is where the sensor outputs are not within the common-mode voltage that the datalogger will accept (±2.5 V for the CR10X). Careful consideration should be made before using an SDM-CVO4 for such a function. Not only is it a relatively expensive method, but it can also result in a less accurate method of sensor measurement (compared to when the datalogger excites the sensors directly) if the precision of the output is critical to the sensor accuracy.
SDM-CVO4 4-Channel Current/Voltage Output Module 6.1 CRBasic SDMCVO4 Instruction This instruction is used to control the SDM-CVO4 four channel current/voltage output device. Syntax SDMCVO4 ( CVO4Source, CVO4Reps, SDMAddress, CVO4Mode ) Remarks This instruction controls the SDM-CVO4, which outputs a voltage or a current. Internal jumpers are used to set the mode for the device, but the jumpers can be overridden with the Mode parameter in this instruction.
SDM-CVO4 4-Channel Current/Voltage Output Module in the device. Use of this mode takes approximately 2 milliseconds additional time per device. When either of these options is used you lose the flexibility of setting the output mode for each channel individually. Additionally, subsequent programs sent to the datalogger must also use an override mode or the power must be cycled on the device to return it to its default state.
SDM-CVO4 4-Channel Current/Voltage Output Module Else WD_0_540 = WD_0_360 EndIf ' Scale the measurements for the SDM-CVO4 to output 0-10000 mV WSOut = WS_ms*200 'WS: 0-50 m/s = 0-10000 mV WDOut = WD_0_540 *18.59 'WD: 0-540 deg = 0-10000mV TempOut= 100*(Temp_C+40) 'Temp: -40-60 deg C = 0-10000 mV RHOut = RH *100 'RH: 0-100 % RH = 0-10000 mV ' Send mV outputs to SDM-CVO4 using the option to override the switch settings SDMCVO4 (CVO4Output(),4,0,10) NextScan EndProg 6.
SDM-CVO4 4-Channel Current/Voltage Output Module location is used to scale the output to 0-10000mV for voltage mode, or 0-20 mA for current output mode. In most applications a specific range of a measured value is scaled to utilize the full scale output of SDM-CVO4. For instance, a temperature sensor reading in the range of -20°C to +50°C would be scaled so at -20C the output is 0 mV and at +50°C the output is 10000 mV.
SDM-CVO4 4-Channel Current/Voltage Output Module Setting the Reps parameter to 0 (Zero) will cause the addressed SDM-CVO4 to shut down, turning off all its outputs. It will turn on channels 1 and 2 at the next execution of Instruction P103 where the reps parameter is 1 or 2. If the reps parameter is greater than 2, then all the channels will be turned on. Refer to the manual for the datalogger being used for full details of the execution time of Instruction 103.
SDM-CVO4 4-Channel Current/Voltage Output Module ; Measure the wind direction from a potentiometer windvane 2: Excite-Delay (SE) (P4) 1: 1 Reps 2: 14 1000 mV, Fast Range 3: 1 SE Channel 4: 1 Excite all reps w/Exchan 1 5: 1 Delay (units 0.01 sec) 6: 1000 mV Excitation 7: 2 Loc [ WindDir ] 8: 0.357 Mult ; Scale to angle in degrees 9: 0.0 Offset ; Measure air temperature from a 107 probe 3: Temp (107) (P11) 1: 1 Reps 2: 2 SE Channel 3: 31 Excite all reps w/E1, 50Hz, 10ms delay 4: 3 Loc [ AirT ] 5: 1.
SDM-CVO4 4-Channel Current/Voltage Output Module ; As we have four channels to output, we will first copy the ; current readings with P54, block move, in a block of four ; input locations to hold the scaled outputs 9: Block Move (P54) 1: 4 No. of Values 2: 1 First Source Loc [ WindSpeed ] 3: 1 Source Step 4: 5 First Destination Loc [ ScldOut_1 ] 5: 1 Destination Step ; Then apply the scaling with one Instruction P53 ; The readings are scaled -5000 to +5000, i.e.
SDM-CVO4 4-Channel Current/Voltage Output Module ; Then apply the scaling with one instruction P53 ; The readings are scaled -3000 to +5000, i.e. to ; cover the range which would equate to ; 4-20 mA in current mode. ; Windspeed to cover the range 0-100 m/s ; Wind direction to cover 0-360 degrees ; Temperature -25 to +50 degrees C ; Radiation 0 - 1000 m^2/s 10: Scaling Array (A*Loc+B) (P53) 1: 5 Start Loc [ ScldOut_1 ] 2: 80 A1 ; WS multiplier 3: -3000 B1 ; WS Offset 4: 22.2222 A2 5: -3000 B2 6: 106.
SDM-CVO4 4-Channel Current/Voltage Output Module ; Now update the SDM-CVO4 with the information ; for the four channels 16: SDM-AO4 (P103) 1: 4 Reps 2: 30 SDM Address 3: 5 Loc [ ScldOut_1 ] 6.5.3 Providing Isolated Power Supplies to Sensors This program example sets all the outputs of the SDM-CVO4 to 10 V to provide isolated power supplies to four separate sensors. The program includes code to put the SDM-CVO4 into standby mode after the measurements are made.
SDM-CVO4 4-Channel Current/Voltage Output Module ; Wait 100 ms for it to power-on and the outputs to stabilize ; You may need to increase this delay if the sensors ; themselves ; have a power-on delay 3: Excitation with Delay (P22) 1: 1 Ex Channel 2: 0000 Delay W/Ex (units = 0.01 sec) 3: 10 Delay After Ex (units = 0.01 sec) 4: 0000 mV Excitation ; Take the four measurements from the Pressure sensors. 4: Volt (Diff) (P2) 1: 4 Reps 2: 04 250 mV Slow Range 3: 1 DIFF Channel 4: 5 Loc [ Press_1 ] 5: 1.
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