VT1532A Eight-Channel Current Output Signal Conditioning Plug-on
Contents
1. VT1532A Eight Channel Current Output Signal Conditioning Plug on User s Manual Enclosed is the User s Manual for the VT1532A Signal Conditioning Plug on Insert this manual in your VXI Module s User s Manual behind the Signal Conditioning Plug ons divider APPLICABILITY This SCP is used with the VT1415A and VT1419A 7 VXI Technology Copyright VXI Technology Inc 2003 Manual Part Number 82 0090 000 Printed June 9 2003 Printed in U S A VT1532A Eight Channel Current Output Signal Conditioning Plug on Introduction The VT1532A provides an eight channel non isolated current source Each output can source 10 mA with up to 15 volt compliance Each VT1532A output can detect an over voltage condition About this Manual This manual shows you how to control the Signal Conditioning Plug on SCP using SCPI commands and explains the capabilities of this SCP The contents of this manual are e Installation ecenin eia e cee eee 3 e Identifying the Plug on 0 0 0 2 eee eee 3 e Field Wiles ai Raine Ba Bank 4 e Programming With SCPI Commands 5 e Programming with the Algorithm Language 5 e Sensing Output Current 0 00 0 6 e Over Voltage Protection 00 c eee eee 7 e RST and TST important 222 2er 7 e SCP Calibration usa a ee nr 7 e Specifications 2 eee cee 8 Installation Installation for this Plug on2. is common to several others and is covered in Chapter 1 of your VXI Module User s Manual Identifying the Plug on You ll find the VTI Technology part number on the connector side of the SCP to the left of the serial number bar code For the VT 1532A the part number is VT1532A VT1532A Current Output SCP 3 Field Wiring VT1532A Channel Since this Current Output SCP is NOT ISOLATED it is extremely important not to introduce ground current loops in the individual channel wiring To avoid this make sure you follow the recommended wiring diagram that follows chassis ground current output HI Good Shielded Twisted Pair Good en Shielded Twisted Pair chassis ground Z VT1532A Channel current output HI LO Guard VT1532A Channel chassis ground Z current output HI Not Recommended Shielded Twisted Pair Voltage difference between these grounds causes current and offset voltage in LO wire I oor Isolator Figure 1 Recommended Field Wiring Isolated Input Actuator Non Isolated Actuator 4 VT1532A Current Output SCP The following table maps SCP channels to Terminal Module terminal names Also see the Terminal Module labels supplied with your VT1532A SCP s SCP 0 SCP 1 SCP 2 SCP3 SCP 4 SCP 5 SCP 6 SCP 7 Channel channels cha
3. 0 query SCP type ch 0 e nter statement here enter response string Programming with the VT1415A Algorithm Language The following example shows the command sequence platform language independent to send values to the SCP output channels It assumes the SCP is installed in SCP position 0 Use SCP positions 4 7 for the VT1419A alg_string first algorithm source in string variable static float chan_0 chan_1 chan_2 chan_3 define algorithm variable these static float chan_4 chan_5 chan_6 chan_7 will default to zero at first 0100 chan_0 algorithm execution 0101 chan_1 0102 chan_2 0103 chan_3 VT1532A Current Output SCP 5 0104 chan_4 0105 chan 5 0106 chan_6 0107 chan_7 ALG DEF ALG1 alg_string send SCPI command to define algorithm ALG1 INIT start algorithm using default trig sys setup Algorithm sets starting channel values to zero The following example shows how your application program can change channel output values while the algorithm is running ALG SCALAR ALG1 chan_0 0 010 ALG SCALAR ALG1 chan_1 0 010 ALG SCALAR ALG1 chan_2 0 005 ALG SCALAR ALG1 chan_3 0 001 ALG SCALAR ALG1 chan_4 0 008 ALG SCALAR ALG1 chan_5 0 010 ALG SCALAR ALG1 chan_6 0 095 ALG SCALAR ALG1 chan_7 0 000 ALG UPDATE must command VT1415A to update the algorithm varia
4. 32A can sense an over voltage condition on any of its outputs This is to protect the SCP and the module it is installed on from damaging voltage levels applied to its outputs If greater than approximately 21 volts is applied to an output channel the SCP may signal the VXI module to open all of its Calibration Protection relays The module will then generate an error message in its error queue read by SYST ERR and set a status bit in its STAT QUES COND register Note The over voltage protect condition can only be reset by issuing the command RST or by cycling power to the module RST CAL and TST Important During execution of RST CAL and TST the outputs of the VT1532A will be disconnected momentarily from your system When the operation is completed outputs will be programmed to output approximately 0 mA The RST command is typically used at the beginning of all application programs Make sure the design of your system takes into account this RST behavior SCP Calibration The VT1415A calibrates all channels of this SCP when the CAL or CALibration SETup commands are sent If this SCP is replaced with a different VT1532A or this SCP is moved to a different SCP location the calibration must be repeated By default the VT1415A uses the Least Squares Curve Fitting method to determine the gain and offset calibration constants for each VT1532A channel This maximizes the overall channel accuracy see Voltage Output Accur
5. Accuracy 0 004 C Offset Error 0 3 uA C Current Output Accuracy 90 days 23 C 1 C with CAL done after 1 hr warm up and applied load is 500 Q 0 06 of expected output 3 3 uA Offset Error Power Required 5 Volts Typical 11 mA Maximum 15 mA 24 Volts With 0 mA into 250 Q Typical 60 mA Max 75mA With outputs at 10mA Typical 135 mA Max 150 mA 8 VT1532A Current Output SCP
6. acy in specifications section Because the Least Squares Curve Fit method does not force the output at a programmed zero to be zero there can be up to 3 3 wA error at this point By sending then DIAG CAL SETUP 1 command before you send the CAL or CAL SET commands all VT1532A and VT1531A outputs will be calibrated to reduce the error at their programmed zero point The trade offis that this can approximately double the error at the VT1532A s 125 yA point The specifications then become 0 06 of expected output 5 7 yA offset DIAG CAL SETUP 1 or RST before the next CAL restores the Least Squares Fit calibration VT1532A Current Output SCP 7 Specifications These specifications for the VT1532A reflect its performance while installed on your VXI module These specifications are not to be added to those presented in your VXI module User s Manual General Specifications Maximum voltage applied to any Damage level gt 42 V peak output Hi terminal Current Output Range at least 10 mA Full Scale at greater than 15 Volt compliance multiple channels can be connected in parallel to provide additional current Current Resolution 16 bits monotonic to 16 bits 316 nA Output Impedance greater than 600 kQ Noise lt 2 uA rms 20 Hz 250 kHz into 250 Q Output Settling Time 350 us with 250 Q load Temperature Coefficient for change in temperature from CAL after 1 hr warm up
7. ble Sensing Output Current Each channel has a 69 Ohm current sense resistor in series with its output The analog input channel associated with each output channel is connected across this current sense resistor Reading a channel returns the voltage developed across its current sense resistor The value input from these channels is related to the output current by the formula VoltageRead for example 69 Current 0100 current_output program the output current for channel O readback 1100 69 current sense channel divided by 69 Ohms Notes 1 This readback value is only an approximation of the actual output current The SCP s output current is calibrated to specification each time you execute the CAL command The input channels for this SCP are not calibrated by CAL The programmed current output value will be more accurate than the sense value The sense value is used only to verify the approximate programmed current 2 An overload reading returned from one of the sense channels does not indicate an overcurrent condition It indicates that the channel s HI terminal has exceeded the voltage input range of the channel This can occur when the channel output is programmed to 0 but is not connected to a load This will occur when the channel is programmed to output current and is not connected to a load 6 VT1532A Current Output SCP Over Voltage Protection As was mentioned in the first paragraph the VT15
8. nnels channels channels channels channels channels channels OHI amp LO OH amp L 8H amp L 16H amp L 24H amp L 32H8L 40H8L 48H8L 56H8L 1 HI amp LO 1H amp L 9H8L 17H8L 25H amp L 33 H amp L 41H8L 49H8L 57 H8L 2HI amp LO 2H amp L 10H8L 18H8L 26H8L 34H8L 42H amp L 50H8L 58H 8 L 3 HI amp LO 3H8L 11H8L 19H8L 27H8L 35H8L 43H8L 51H8L 59H8L 4HI amp LO 4H amp L 12H amp L 20H amp L 28H amp L 36H8L 44H8L 52H8L 60H amp L 5 HI amp LO 5H amp L 13H amp L 21H amp L 29H amp L 37H8L 45H8L 53H 8 L 61H8L 6 HI amp LO 6H8L 14H8L 22H amp L 30H8L 38H8L 46H8L 54H8L 62H8L 7HI amp LO 7H8L 15H8L 23H amp L 31H8L 39H8L 47H8L 55H amp L 63 H amp L Programming With SCPI Commands Checking the ID of the SCP The only SCPI command shown here is used to query the SCP s identification string Your VXI Module may or may not support SCPI commands to control the SCP s output amplitude Check for OUTPut subsystem commands in the SCPI Command Reference of your VXI Module s User s Manual To verify the SCP type s installed on your VXI module use the SYSTem CTY Pe lt channel gt command e The channel parameter specifies a single channel in the channel range covered by the SCP The first channel number for each of the eight SCP positions are 0 8 16 24 32 40 48 and 56 The value returned for the VT1532A SCP is HEWLETT PACKARD E1532A 8 Channel Current Output SCP 0 0 To determine the type of SCP installed on channels 0 through 7 send SYST CTYP 10
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