Sensoray 518 Bedienungsanleitung

Sensoray Model 518 PCbus Sensor Coprocessor Revised July 25, 2001 For Technical Support contact Sensoray Co., Inc. 7

9 Hardware Filters Each channel is provided with a hardware filter, which may be used to reduce thermocouple and aid in detecting open sensor condi

10Programming Programming of the 518 is achieved via a set of built-in commands. Commands are sent from the PC104 master (aka “host”) to the 518. So

11 Status Register The status register provides the host with information used for coprocessor status monitoring and communication handshake contro

12Control Register The control register provides the means for host management of interrupts and coprocessor soft reset. D7 D6 D5 D4 D3 D2 D1

13 Sample Low-level Drivers We recommend that you incorporate procedures in your application software that will conceal the handshake protocol from

14‘ ******************* QUICKBASIC DRIVERS ********************* ‘ This subprogram handshakes a byte to the 518 command register: SUB Send518Byte (B

15/******************************** C DRIVERS ****************************/ /* ADSENDBYTE handshakes a command byte to the 518 command register */

16Commands The 518 is accessed through a simple yet powerful built-in command set. Commands vary in length depending on the size of encapsulated dat

17 Declare Channel Sensor This command declares the type of sensor connected to a channel. Typically, this command is executed once for each channel

18 Set Filter Time Constant This command establishes a software single-pole low-pass filter for the specified channel. The second command byte speci

1Table of Contents BASICS: Read Firmware Version. . 32 Limited Warranty . . 3 Read Product I.D. . . 33 Special Handling Instru

19 Read Board Temperature This command returns the temperature at the optional 7409TC termination board. Useful for monitoring the temperature of th

20Read Channel Data This command returns the most recently acquired sensor data from a channel. The returned integer value is scaled as a function o

21Read Data From All Channels This command returns the most recent sensor data from all eight channels, starting with channel 0. Data is returned fr

22Set Channel Alarm Limits This command declares upper and lower alarm limits for a channel. An alarm will ‘sound’ if channel sensor data strays out

23Set Open Sensor Data Values This command establishes open sensor data values for all channels. The second command byte contains eight flags, one f

24Read Alarm Flags This command returns the status of all channel alarms in two response bytes. The first response byte contains the status of all h

25Set Gage Zero This command sets the zero-load value on a strain gage channel. In effect, the Set Gage Zero command tells the 518 that there is pre

26Set Gage Span This command sets the effective gain of a strain gage. Many gage installations simulate gage loads by multiplexing a simulated zero

27Tare Gage This command will tare the strain/pressure gage connected to a single channel. The Tare Gage command may be used to compensate for the w

28Read Gage Calibration This command returns the internal slope and offset from a strain gage channel. The response string is six bytes long. The fi

2 Limited Warranty Sensoray Company, Incorporated (Sensoray) warrants the model 518 hardware to be free from defects in material and workmanship a

29Set Gage Calibration This command transfers strain gage slope and offset parameters to the coprocessor for a specific strain gage channel. Typical

30High Speed Mode This command increases the channel scan rate to allow higher throughput. The default channel processing time is decreased from 22

31Low Power Standby This command places the sensor coprocessor in a low-power standby mode. Power consumption is reduced by halting the logic clock,

32Read Firmware Version This command returns the coprocessor firmware version number times 100. The firmware version number is printed on the EPROM

33Read Product I.D. This command returns an identifier specific to the addressed Sensoray product. The product identifier specifies the Sensoray pro

34Set Coefficients This command defines the linearization coefficients for a channel previously declared as a USER-DEFINED RESISTIVE SENSOR. Three c

35 EXAMPLE: ‘ Channel 2 is connected to a linear slide potentiometer. It is ‘ necessary to measure the potentiometer’s position as a function ‘ of

36Calibrate 518 This command calibrates coprocessor internal standards. All measurements made by the coprocessor are referenced to these standards.

37Sensor Tables Sensor Type Code Data Scaling/Bit Voltage +/- 100 mV f.s. +/- 500 mV f.s. +/- 5V 17H 16H 15H 5 microvolts 20 microvolts 200 mic

38 Back Compatibility In addition to the sensor definition codes listed above, several additional codes exist to maintain compatibility with the ea

3Special Handling Instructions The Model 518 circuit board contains CMOS circuitry that is sensitive to Electrostatic Discharge (ESD). Special care

39Sensor Connections All sensors are connected to the 518 by means of connector P1. Optionally, sensors may be connected to the Sensoray model 7409T

40 A three-wire RTD still has half the cable loss of the equivalent two-wire RTD. To eliminate cable losses entirely, the four-wire circuit must be

41Thermocouple and DC Voltage Thermocouples and DC voltages are connected directly to the V+ and V- terminals. Thermocouples and DC voltage sources

42Thermistor/Custom Resistive Sensors In the following discussion, thermistor is used interchangeably with custom resistive sensor. Thermistors have

434 to 20 mA Current Loops The coprocessor supports 4-20 mA current loop inputs on any channel, however, a 250-ohm 0.01% resistor must be installed

44Sensor Specifics User-defined Resistive Sensors User-defined resistive sensors may be interfaced to the coprocessor subject to these constraints:

45CALL Send518Byte (192 + 5) ‘ declare channel 5 linearization coefficients: CALL Send518Real (.19) ‘ A CALL Send518Real (24.1) ‘ B CALL Send51

46Verifying Thermocouple Calibration Thermocouple applications sometimes require periodic validation of thermocouple calibration. Two methods are co

474. Use the NBS tables to obtain the thermocouple voltage Vsim corresponding to Tsim. Note that Vsim is the corrected thermocoup

48As an example, suppose a gage is rated at 3 mV/V at 100 PSI full scale. The 518 coprocessor would be able to resolve a load to: In order to succe

4 INTRODUCTION Functional Description The 518 interfaces eight process sensors directly to the PC bus. Each of the eight sensor channels may be inde

49Many gage installations achieve zero and span calibration with the aid of gage simulation signals. Each gage produces three signals that are multi

50Theory of Operation Software Execution of the internal coprocessor software is managed by a resident multi-tasking kernel. The kernel is responsib

51Command Processor The command processor fetches and executes commands from the host processor. Top priority is given to this task in order to mini

52standards are switched through dedicated analog switches so as to not rob input channels from the external sensor channels. Next, the selected cha

53 Clearly, the scan time will decrease as the number of active channels decrease. Channels can be removed from the scan loop by disabling them with

54As it turns out, acquisition latency actually takes somewhat longer than the theoretical maximums discussed here. Additional time is consumed by t

55Command Summary READ CHANNEL DATA - read linearized sensor data from one channel command command: (CHAN) response: (HIGH DATA),(LOW DATA) DEFI

56SET GAGE CALIBRATION - download gage calibration data to one channel command: (144 + CHAN), (S0), (S1), (S2), (S3), (S4), (S5) response: N

Specifications General Specifications Parameter Specification Input Power ± 12VDC

6Table 2: Sensor Specifications Sensor Type Range Resolution Accuracy Thermocouple B C E J K N T S R 0C to 1820C 0C to 1820C -270C to 990C -210C

7Hardware Configuration The coprocessor board requires installation of shorting shunts to select hardware options. Hardware configuration must be c

8 Nibble Value High Byte Low Address Byte Low Nibble High Nibble Low Nibble E8 E7 E6 E5 E4 E3 E2 E1 0 Install Install Install Insta