SAB-A USER MANUAL RAPID CONTROLS LDT to Analog Converter
Contents
1. The connection should be established using the parameters shown in table 3 5 To access the setup menu transmit three escape ASCII 27 characters rapidly The SAB A will display a setup menu and prompt for further input The setup menu will display a list of parameters and values Each of these parameters may be changed by transmitting the letter shown next to the parameter In addition to the setup parameters the menu shows the position most recently gathered from the sensors After changes have been made the changed parameters must be committed to non volatile memory or they will be lost when power is removed from the SAB A Choose Save to EEPROM to save all parameters to non volatile memory To exit the setup menu and return to normal operation choose Quit from the menu transmit the letter Q or cycle power to the SAB A Configuration Setup Menu Parameter Configuration Baud Rate 9600 bps Data Bits 8 Parity None Stop Bits 1 Handshaking None Table 3 5 Serial Parameters 3 2 1 Default Configuration A set of default parameters see table 3 6 are stored in the SAB A when it leaves the factory The default parameters can be restored by selecting the Factory Defaults option from the setup menu Setup Item Default Value Transducer Update Time 2 ms Eavesdrop Mode Normal Detected Update Time N A Recirculations No Recirculation Transducer Type 24 bit SSI Velocity Window Size 50 transducer update periods Ana2. 232 485 serial port Status LEDs provide visual confirmation of proper sensor operation A Sensor OK output for each channel allows an external device to monitor sensor interface status Although the SAB A was designed for use with magnetostrictive linear displacement trans ducers it can be used with other types of sensors such as glass scales or encoders To be used with the SAB A a sensor must be compatible with the one of the sensor protocols supported by the SAB A SSI Start Stop or PWM 1 2 Features e Two channels of 24 bit position from Start Stop PWM or SSI magnetostrictive transduc ers 16 bit analog outputs 0 3 mV resolution with selectable output voltage range Voltage range options 10 to 10V 0 to 10V 5 to 5V 0 to 5V Supports arbitrary SSI sensor resolution 56 MHz oscillator provides 0 001 inch resolution with 2 reciculations with Start Stop or PWM sensor Allows controlling all analog outputs from a single sensor with different scaling e Transducer OK output and LED signals valid transducer operation Software selectable update rate velocity window and analog position velocity scaling and offsetting Setup via RS 232 or RS 485 serial interface jumper selectable RS 485 termination Blinking LED indicates good operation of SAB A Watchdog timer for reset upon software failure Non volatile memory for storage of setup parameters Convenient screw terminal connections 4 64 x 5 31 x 1 77 DxHxW inch DIN rail mou
3. sensors other than Start Stop or PWM To determine the resolution per count when using recirculations divide the base resolution by the number of recirculations performed 3 2 2 4 Transducer Type The transducer type selects the protocol used to communicate with the attached sensor Avail able options are SSI 24 SSI 25 Start Stop PWM and Copy Other The SSI options indicate the number of bits returned by the transducer and should be used with SAB A SSI models The Start Stop and PWM settings are to be used with SAB A RPM models The Copy Other option is a special option that causes the selected channel to use the position information from the other channel This mode is designed for operation with a single sensor Although the position information is copied from the other channel the setup items may differ between the channels For example the 22d channel could have a different velocity window size or a different analog range Menu Selection Required Model Sensor Protocol Notes SSI 24 SSI 25 Start Stop PWM Copy Other SAB A SSI SAB A SSI SAB A RPM SAB A RPM Any SSI SSI Start Stop PWM None 24 bit data word 25 bit data word Supports recirculation Supports recirculation Data copied from other channel Table 3 7 Transducer Type Settings 3 2 2 5 Transducer Update Time The transducer update time is the number of milliseconds between each update of the trans ducer position inform
4. 1 10 Ch1 Sensor Status Output JP3 10 Ch 1 Data4 from Sensor JP3 11 Ch 1 Data from Sensor JP4 1 24 or 15VDC Power JP3 12 24 or 15VDC Power to Sensor JP4 2 Power common and signal ground JP3 13 Ground JP4 3 15VDC Power Optional JP3 14 15VDC Power to Sensor if needed J1 1 Pos Ch 0 Position Analog Out J1 1 Vel Ch 0 Velocity Analog Out J1 2 Pos Analog Ground J1 1 Vel Analog Ground J1 3 Pos Ch 1 Position Analog Out J1 1 Vel Ch 1 Velocity Analog Out Table 2 1 SAB A Connector Pinouts Configuration Jumpers and DIP Switches 3 Configuration 3 1 Jumpers and DIP Switches 3 1 1 DIP Switch S1 Dip switch S1 is used to select the desired analog output voltage range for all of the analog output channels The voltage range can be configured to operate with one of these output ranges 10 to 10 V 0 to 10V 5 to 5V and 0 to 5V The SAB A s analog outputs will maintain 16 bit resolution in any of the voltage output ranges Switch Description Switch On Switch Off S1 1 Analog voltage unipolar bipolar select Unipolar Bipolar 81 2 Analog voltage 5V 10V select 5V 10V 81 3 Unused S1 4 Unused S1 5 Unused 51 6 Unused S1 7 Unused S1 8 Unused Table 3 1 Dip Switch S1 Settings For example to configure Channel 1 position output to be 0 to 10V set switch S1 3 On unipolar mode and switch S1 4 Off 10V 3 1 2 Jumper X1 Jumper X1 set at the fact
5. OM Select this item to load the values from the non volatile memory This will revert any changes made since the last time values were saved to non volatile memory 3 2 2 13 Factory Defaults Select this item to change all of the setup values to the factory defaults as shown in Table 3 6 Defaults are not saved to non volatile memory until the Save to EEPROM menu item is selected 3 2 2 14 Quit Select this item to exit setup and return to normal operation The configuration values entered via the setup menu will be in effect at this point Any values not saved to the EEPROM will be lost when power is removed 11 General Operation Startup 4 General Operation 4 1 Startup At power on the board will print a sign on message indicating the date of software in the board and the status of the retrieval of data stored in the non volatile EEPROM A message similar to the following is displayed Rapid Controls Inc SAB A Copyright c 1997 2010 Rapid Controls Inc 03 01 2010 EEPROM load successful 4 2 Sensor Processing The SAB A interfaces with two magnetostrictive transducers and interrogates the sensors for position information at a user defined rate After valid sensor data is received on a sensor interface channel the data is processed as shown in Figure 4 1 Position data history over a user defined window is stored for use in velocity calculation Scaling and offsetting is performed on the position and velocity data befor
6. RAPID CONTROLS 2 SAB A USER MANUAL LDT to Analog Converter Rapid Controls Inc July 9 2010 Rapid City SD USA 2010 Rapid Controls Inc www rapidcontrols com info rapidcontrols com tel 605 348 7688 fax 605 341 5496 Contents Contents 1 Introduction ne Eel Rex RR REX engi Gee SR RACE RA tak SEXES UE 1 1 Description 1 2 Features 1 3 Models and Ordering Information 2 Installation ovv VR VP adve wr VE OOS EE OFT EY MEUS 2 1 Connections 3 Configuration i561 9 br ae ae a aa aaa Ta alg 3 1 Jumpers and DIP Switches 3 2 Setup Menu 4 General Operation 4 p Re RI P ned tend cde ede deca e npa be een 4 1 Startup 4 2 Sensor Processing 4 3 Status Introduction Description 1 Introduction 1 1 Description The SAB A converts two channels of magnetostrictive transducer position and velocity to two or four analog voltage outputs To achieve accurate low latency output the conversion is implemented using micro controller EPLD and 16 bit digital to analog converters The SAB A continually interrogates the sensors for position data at a configurable rate Immediately after each position update velocity data is calculated from the collected position data The analog outputs are then set based on the most recent data available Sensor update rate velocity window size and analog output scaling and offseting are config urable using a text based menu accessible via an RS
7. alculate a velocity value P Pn 4 1 nx Ts Equation 4 1 shows the calculation used to determine velocity V is the velocity in units per second n is the windows size P5 is the current position P n is the oldest position information in the window Ts is the sensor update period in seconds 4 2 3 Scaling and Output After sensor data is received and velocity data is calculated the data is scaled and offset The configuration parameters Analog Position Start Analog Position Range and Analog Velocity Range are used to control this process 4 3 Status A red LED on the board blinks during operation Two green LEDs indicate the status of the transducers A lit LED indicates a good transducer and a dim or dark LED indicates a missing or failing transducer or magnet Sensor status may also be read via the digital outputs 13
8. ation When using a magnetostrictive transducer the update time must be long enough to allow the strain pulse to travel the length of the wand The wavespeed Configuration Setup Menu of a typical magnetostrictive transducer is 9 us inch If recirculations are used multiply the required time by the number of recirculations If the update time is set to a value that does not allow for propogation of the strain pulse the position data will be unstable See Table 3 8 for a list of possible update time settings If the sensor used is not a magnetostrictive transducer configure the update time as in structed by the manufacturer of the sensor Sensor Length in Recirculations Update Time ms 1 100 1 1 101 200 201 300 301 400 1 50 51 100 101 150 200 201 1 25 26 50 51 75 76 100 A A A AJIN wo N N e KF Fe A ww Neje N Le wo N Table 3 8 Suggested Update Times 3 2 2 6 Velocity Window Size The velocity window size determines how many historical position updates are included in the calculation of the velocity output For example if the velocity window size is 10 the current position and the position 10 transducer updates ago are used to calculate the velocity 3 2 2 7 Analog Position Start The analog position start is the number of counts which corresponds to the minimum analog output value 10V 5V or 0V DC Any position less than the analog position start will be output a
9. e output via 16 bit DAC OS Position History Velocity Analog Output Velocity Scaling Velocity Processing Position Analog Output Position Scaling Position Data Sensor Interface Figure 4 1 Sensor Data Processing for One Channel 4 2 1 Sensor Interface Each sensor interface is capable of interfacing with sensors supporting three protocols commonly used with magnetostrictive transducers SSI Start Stop and Pulse Width Modulated PWM Other types of sensors such as absolute encoders laser rangefinders and glass scales support the SSI protocol and are compatible with the SAB A SAB A SSI models support SSI protocol sensors SAB A RPM models support Start Stop and PWM protocol sensors 12 General Operation Status Each sensor interface can operate in one of two modes normal mode and eavesdropping mode In normal mode the sensor is interrogated at a fixed update rate In eavesdropping mode an external master device must interrogate the sensor The SAB A monitors the com munications between the external master and the sensor Position data is stored each time the sensor is interrogated 4 2 2 Velocity Calculation After position data is received the data is stored in a circular queue This queue holds a configurable amount of historical position data Each time new position data is received this position data along with the historical position data is used to c
10. log Position Start 0 counts Analog Position Range 100000 counts Analog Velocity Range 100000 counts s Velocity Output Type Velocity Table 3 6 SAB A Default Configuration 3 2 2 Configuration Parameters 3 2 2 1 Eavesdrop Mode Eavesdropping mode allows the SAB A to monitor data from a sensor that an external device is interrogating When eavesdrop mode is enabled the SAB A monitors the communication between the external devices and the sensor to collect sensor data The sensor update period is automatically detected Eavesdrop mode can be set to one of two modes Normal or Eavesdrop In normal mode the sensor is interrogated by the SAB A In eavesdrop mode the sensor is interrogated by an external device Configuration Setup Menu 3 2 2 2 Detected Update Time The detected update time is a read only value that is only valid when operating in eavesdrop mode see 3 2 2 1 The update time is detected by monitoring the interrogate pulses received from the external device that is interrogating the sensor When operating in normal non eavesdrop mode this value should be ignored the update period can be set by changing the Transducer Update Time setup item 3 2 2 3 Recirculations Recirculations are a method of increasing the effective resolution of a Start Stop or PWM magnetostrictive transducer by repeatedly interrogating the sensor The recirculations para meter sets the number of times the sensor will be interrogated It is ignored for
11. nt enclosure Introduction Models and Ordering Information 1 3 Models and Ordering Information Table 1 1 shows the available SAB A models SAB A units are available with 2 or 4 analog outputs and with support for SSI or Start Stop and PWM sensors Model Number Channels Sensor Interface Position Output Velocity Output SAB A RPM PA 2 Start Stop amp PWM 2x 16 bit SAB A RPM VA 2 Start Stop amp PWM 2x 16 bit SAB A RPM PA VA 2 Start Stop amp PWM 2x 16 bit 2x 16 bit SAB A SSI PA 2 SSI 2x 16 bit SAB A SSI VA 2 SSI 2x 16 bit SAB A SSI PA VA 2 SSI 2x 16 bit 2x 16 bit Table 1 1 SAB A Models and Ordering Information Installation Connections 2 Installation 2 1 Connections Figure 2 1 shows the location of the connectors on the SAB A 10 JP1 1 z E o ES ola u o 9 Figure 2 1 SAB A Connector Placement Table 2 1 shows the pinout of the connectors on the SAB A Installation Connections Pin Function Pin Function JP1 1 Logic Ground JP3 1 Ch 0 Clock4 to Sensor JP1 2 RS 232 RX from Host JP3 2 Ch 0 Clock to Sensor JP1 3 RS 232 TX to Host JP3 3 Ch 0 Data4 from Sensor JP1 4 RS 485 TxD RxD RS 485 A JP3 4 Ch 0 Data from Sensor JP1 5 RS 485 TxD RxD RS 485 B JP3 5 24VDC Power to Sensor JP1 6 Input 1 JP3 6 Ground JP1 7 Input 2 JP3 7 No Connect JP1 8 Input Common JP3 8 Ch 1 Clock to Sensor JP1 9 Ch0 Sensor Status Output JP3 9 Ch 1 Clock to Sensor JP
12. ory and cannot be changed 3 1 3 Jumper X2 Jumper X2 selects the serial communications interface to be used Shunt Placement Serial Interface 1 2 RS 485 EIA 485 2 3 RS 232 Table 3 2 Jumper X2 Settings Configuration Setup Menu 3 1 4 Jumper X3 Jumper X3 configures RS485 line termination resistors Termination reduces noise on long gt 2000 m RS 485 networks Termination resistors should be used on the ends of the networks only Shunt Placement Termination No Shunts No termination installed 1 2 amp 3 4 Bias resistors and 120 2 parallel termination resistor Table 3 3 Jumper X3 Settings 3 1 5 Jumper X4 Jumper X4 sets the output mode of the sensor status outputs sinking or sourcing The status outputs must be configured to match the common applied to JP1 8 If ground is applied to JP1 8 the outputs must be sinking If a voltage 12 to 24 VDC is applied to JP1 8 the outputs will source the voltage Shunt Placement Output Mode JP1 8 Connection 1 3 5 7 2 4 amp 6 8 Sinking Ground 1 2 3 4 5 6 amp 7 8 Sourcing 12 to 24 VDC Table 3 4 Jumper X4 Settings 3 2 Setup Menu Configuration of the SAB A is accomplished through an interactive setup menu The setup items accessable in this menu are stored in non volatile memory The setup menu can be accessed via an RS 232 or RS 485 serial connection using a computer or other terminal device connected to the JP1 connector
13. s the minimum analog output value 3 2 2 8 Analog Position Range The analog position range parameter sets the number of counts covered by the total range of the analog position output For example if the analog output voltage range is 10 to 10V analog position start is 5000 and analog position range is 25000 output will be 10V at 5000 or less counts OV at 17500 counts and 10V at 30000 counts and higher 10 Configuration Setup Menu 3 2 2 9 Analog Velocity Range The analog velocity range parameter sets the number of counts sec covered by each half of the analog velocity output For example if the analog output voltage range is 10 to 10V and the analog velocity range is 20000 the output will be 10V at 20000 counts sec 0V at 0 counts sec and 10V at 20000 counts sec OV is always output when the speed is 0 counts second 3 2 2 10 Velocity Output Type The analog velocity output type parameter controls the style of the velocity analog outputs One of two options may be selected velocity or speed When speed is selected the absolute value of the velocity is output When speed is selected a speed of zero is output as the lowest possible analog output voltage when velocity is selected a velocity of zero is output at the center of the voltage range 3 2 2 11 Save to EEPROM Select this item to save the values to non volatile memory Any configuration items changed will not be saved until this is selected 3 2 2 12 Load from EEPR
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