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D5000 SERIES USERS MANUAL

1. and Y This designates the colors used on standard 4 wire telephone cable Label Color B GND Black R V Red G DATA Green Y DATA Yellow This color convention is used to simplify installation If standard 4 wire telephone cable is used it is only necessary to match the labeled pins with the wire color to guarantee correct installation DATA on the label is the complement of DATA negative true To minimize unwanted reflections on the transmission line the bus should be arranged as a line going from one module to the next Tree or random structures of the transmission line should be avoided When using long transmission lines and or high baud rates the data lines should be termi nated at each end with 200 ohm resistors Standard values of 180 ohms or 220 ohms are acceptable During normal operation there are periods of time where all RS 485 drivers are off and the communications lines are in an idle high impedance condition During this condition the lines are susceptible to noise pickup which may be interpreted as random characters on the communications line To prevent noise pickup all RS 485 systems should incorporate 1K ohm bias resistors as shown in Figure 3 2 The resistors will maintain the data lines in a mark condition when all drivers are off A1000 series converter boxes have the 1KQ resistors built in The resistors are user selectable via dip switch located on the rear panel of the A100
2. A D Hex Binary D Hex Binary L 76 4C 01001100 204 CC 11001100 M 77 4D 01001101 205 CD 11001101 N 78 4E 01001110 206 CE 11001110 O 79 4F 01001111 207 CF 11001111 P 80 50 01010000 208 DO 11010000 Q 81 51 01010001 209 Di 11010001 R 82 52 01010010 210 D2 11010010 S 83 53 01010011 211 D3 11010011 T 84 54 01010100 212 D4 11010100 U 8 55 01010101 213 D5 11010101 V 86 56 01010110 214 D6 11010110 W 87 57 01010111 215 D7 11010111 X 88 58 01011000 216 D8 11011000 Y 89 59 01011001 217 D9 11011001 Z 90 DA 01011010 218 DA 11011010 91 DB 01011011 219 DB 11011011 92 5C 01011100 220 DC 11011100 93 5D 01011101 221 DD 11011101 A 94 DE 01011110 222 DE 11011110 _ 95 5F 01011111 223 DF 11011111 i 96 60 01100000 224 EO 11100000 a 97 61 01100001 225 E4 11100001 b 98 62 01100010 226 E2 11100010 c 99 63 01100011 227 E3 11100011 d 100 64 01100100 228 E4 11100100 e 101 65 01100101 229 E5 11100101 f 102 66 01100110 230 E6 11100110 g 103 67 01100111 231 E7 11100111 h 104 68 01101000 232 E8 11101000 i 105 69 01101001 233 E9 11101001 j 106 6A 01101010 234 EA 11101010 k 107 6B 01101011 235 EB 11101011 108 6C 01101100 236 EC 11101100 m 109 6D 01101101 237 ED 11101101 n 110 6E 01101110 238 EE 11101110 o 111 6F 01101111 239 EF 11101111 p 112 70 01110000 240 FO 11110000 q 113 71 01110001 241 F4 11110001 r 114 72 01110010 242 F2 11110010 s 115 73 01110011 243 F3 11110011 t 116 74 01110100 244 F4 11110100 A D Hex Binary D Hex Binary u 117 75 01110101 245
3. CZ The Clear Zero command clears the channel output offset register value to 00000 00 The D5000 series modules contain an output offset register for each channel Specify the correct channel address with this command to clear the proper output offset register This command clears any data resulting from a Trim Zero TZ Command 1CZ Response Command 1CZ Response 1CZF8 IDentification ID The IDentification command allows the user to write a message into the internal nonvolatile memory which may be read back at any time using the Read IDentification RID command The message may be up to 16 characters long and has no effect on the module operation Useful informa tion such as the module location calibration date or model number may be stored for later retrieval The ID command is write protected and checksums are not supported The module will abandon any ID command with a message length in excess of 16 characters Command 1IDBOILER ROOM Response Command 1IDBOILER ROOM Response 1IDBOILER ROOM02 Read Block of data The Read Block of data command is used to read data values from all used channels in a D5000 series module Since the read data command is the most frequently used command in normal operation the read block of data command provides a special shorthand way of reading data The read block of data command decreases communications time by removing the need to send a command for every response Th
4. F5 11110101 v 118 76 01110110 246 F6 11110110 w 119 77 01110111 247 F7 11110111 x 120 78 01111000 248 F8 11111000 y 121 79 01111001 249 FQ 11111001 z 122 7A 01111010 250 FA 11111010 123 7B 01111011 201 FB 11111011 124 7C 01111100 202 FC 11111100 125 7D 01111101 203 FD 11111101 126 7E 01111110 254 FE 11111110 12 7F 01111111 255 FF 11111111 Appendix B D5000 Specifications Specifications typical 25 C and nominal power supply unless otherwise noted Analog e Four analog input channels e Maximum CMV input to output at 60Hz 500V rms e Leakage current input to output at 115Vrms 60Hz lt 2LA rms e 15 bit measurement resolution e 8 conversions per second e Autozero 8 autocalibration no adjustment pots Digital 8 bit CMOS microcomputer Digital scaling linearization and calibration e Nonvolatile memory eliminates pots and switches Digital filtering Small and large signal with user selectable time constants from 0 to 64 seconds Communications e Communications in ASCII via RS 232C RS 485 ports Selectable baud rates 300 600 1200 2400 4800 9600 19200 38400 57600 115200 e NRZ asynchronous data format 1 start bit 7 data bits 1 parity bit and 1 stop bit e Parity odd even none e User selectable channel address e ASCII format command response protocol e Communications distance up to 4 000 feet RS 485 e Transient suppression on RS 485 communications lines Comm
5. TIME DELAYS 4 BYTE TIME DELAYS 6 BYTE TIME DELAYS Byte 4 This setup byte specifies the number of displayed digits and the digital filter time constants Number of displayed digits For ease of use the data outputs of all modules are standardized to a common 7 digit output consisting of sign 5 digits decimal point and two more digits Typical output data looks like 00100 00 However best case resolution of the A D converter is 1 part in 32 768 In some cases the resolution of the output format is much greater than the resolution of the measurement system In such cases the trailing digits of the response would display meaningless information Bits 6 and 7 are used to insert trailing zeros into the output data to limit the output resolution and mask off meaningless digits Bit7 Bit6 0 0 XXXX0 00 4 displayed digits 0 1 XXXXX 00 5displayed digits 1 0 XXXXX X0 6displayed digits 1 1 XXXXX XX 7 displayed digits For example the D5311 model for thermocouples has 1 0 degree output resolution The appropriate number of digits for this module is 5 to mask off the 0 xx digits which have no meaningful data In some cases the user may want to limit the output resolution to 10 degrees To do this select bits 6 and 7 to display 4 digits With this selection the right most three digits will always be set to 0 The number of displayed digits affects only data received from an RD or ND command Large Signal Fi
6. WE command Write Extended Address WEA The Write Extended Address WEA command allows the user to set the two byte address to be used with Extended Addressing see Chapter 7 The argument of the command specifies the hex ASCII values of the two characters to be used as the Extended Address For example if the address is to be set for characters 01 Command 1WEA3031 Response Command 1WEA3031 Response 1WEA3031FF Note that 30 and 31 are the hex ASCII values for characters 0 and 1 respectively The EA command is write protected and must be preceded with a WE command The address data may be read back with the Read Extended Address REA command Write MaXimum displayed value WMX Write MiNimumdisplayed value WMN The MaXimum MX and MiNimum MN commands are used to rescale the input ranges of D5000 modules to units that may be more appropriate to a particular application Command 1WMX 00020 00 Response Command 1WMX 00020 00 Response 1WMX 00020 00AB Command 1WMN 00000 00 Response ba Command 1WMN 00000 00 Response 1WMN 00000 009F The Write MiNimum displayed value WMN command assigns an output data value corresponding to the full scale analog output value The Write MaXimum displayed value MX command assigns an output data value corresponding to the full scale analog output value Let s say that you want to scale an input to desired engineering units For example ma
7. being used in a RS 232 daisy chain communica tions configuration then ensure that the Echo Bit is enabled in the setup SU message of each module 8 If the problem is not corrected after completing the steps above then connect the module by itself to a Host computer as outlined in Chapter 1 0 under Quick Hook up Start the supplied Utility software and please call the factory for further assistance e RS 485 Module is not responding to commands 1 Perform steps 1 2 4 5 and 6 listed above 2 Ensure that module RS 485 Data line module terminal pin 7 is connected to the Host RS 485 Datat line 3 Ensure that module RS 485 Data line module terminal pin 8 is connected to the Host RS 485 Data line 4 If the problem is not corrected after completing the steps above then connect the module by itself to a Host computer as outlined in Chapter 1 0 under Quick Hook up Start the supplied Utility software and please call the factory for further assistance Error in displayed value Make sure that the C F bit is set to a 0 Otherwise the values will be scaled by the F equation Read Data RD values are factor of two times normal values Ensure that the Degree C Degree F bit in the setup SU message is set to Degree C Module responds with 1 COMMAND ERROR to every command Ensure that characters in the command message are uppercase char acters All commands consist of uppercase characters only e Character
8. module types The Setup command uses hexadecimal representations of data The data structure for this command is detailed in the command description Write Protection Many of the commands listed in Table 4 1 are under the heading of Write Protected Commands These commands are used to alter setup data in the module s EEPROM They are write protected to guard against accidental loss of setup data All write protected commands must be preceded by a Write Enable WE command before the protected command may be executed Miscellaneous Protocol Notes The address character must transmitted immediately after the command prompt character After the address character the module will ignore any character below ASCII 23 except CR This allows the use of spaces ASCII 20 within the command message for better readability if desired The length of a command message is limited to 20 printable characters If a properly addressed module receives a command message of more than 20 characters the module will abort the whole command sequence and no response will result If a properly addressed module receives a second command prompt before it receives a CR the command will be aborted and no response will result Response Structure Response messages from the module begin with either an asterisk ASCII 2A or a question mark ASCII 3F prompt The prompt indicates acknowledgment of a valid command The pr
9. refers to lowest order bit bitnumber 7 6 5 4 3 2 1 0 binary data 00 1 1 0 0 0 1 31 hex The SU command is write protected to guard against erroneous changes in the setup data therefore each SU command must be preceded by a Write Enable WE command To abort an SU command in progress simply send a non hex character an X for example to generate a SYNTAX ERROR and try again CAUTION Care must be exercised in using the SU command Improper use may result in changing communications parameters address baud rate parity which will result in a loss of communications between the host and the module In some cases the user may have to resort to using Default Mode to restore the proper setups The recommended procedure is to first use the Read Setup RS command to examine the existing setup data before proceeding with the SU command Byte 1 Byte 1 contains the module base channel address The module contains four channels but only the base channel or channel 0 address is specified in the SetUp message The microprocessor automatically assigns the next three consecutive ASCII values as channel addresses for channels one thru 3 The address is stored as the ASCII code for the string character used to address channel0 of the module In our example command 1SU31070080 the first byte 31 is the ASCII code for the character 1 If our sample command is sent to a module the EEPROM will be loaded with the address r which i
10. the self calibration period will result ina NOT READY error When this occurs simply wait a couple seconds and repeat the command The module may be reset in three ways a power up reset a Remote Reset RR command or an internal reset All modules contain a watchdog timer to ensure proper operation of the microprocessor The timer may be tripped if the microprocessor is executing its program improperly due to power transients or static discharge If the NOT READY error persists for more than 30 seconds check the power supply to be sure it is within specifications PARITY ERROR A parity error can only occur if the module is setup for ever or od parity Usually a parity error results from a bit error caused by interference on the communications line Random parity errors are usually overcome by simply repeating the command If too many errors occur the communications channel may have to be improved or a slower baud rate may be used A consistent parity error will result if the host parity does not match the module parity In this situation the easiest solution may be to change the parity in the host to obtain communication At this point the parity in the module may be changed to the desired value with the SetUp SU command The parity may be changed or turned off by using Default Mode SYNTAX ERROR A SYNTAX ERROR will result if the structure of the command is not correct This is caused by having too few or too many char
11. 0 Special care must be taken with very long busses greater than 1000 feet to ensure error free operation Long busses must be terminated as de scribed above The use of twisted cable for the DATA and DATA lines will greatly enhance signal fidelity Use parity and checksums along with the form of all commands to detect transmission errors In situations where many modules are used on a long line voltage drops in the power leads becomes an important consideration The GND wire is used both as a power connection and the common reference for the transmission line receivers in the modules Voltage drops in the GND leads appear as a common mode voltage to the receivers The receivers are rated for a maximum of 7V of common mode voltage For reliable operation the common mode voltage should be kept below 5V To avoid problems with voltage drops modules may be powered locally rather than transmitting the power from the host Inexpensive calculator type power supplies are useful in remote locations When local supplies are used be sure to provide a ground reference with a third wire to the host or through a good earth ground With local supplies and an earth ground only two wires for the data connections are necessary Communications Delay All D5000 modules with RS 485 outputs are setup at the factory to provide two units of communications delay after a command has been received see Chapter 5 This delay is necessary when using host
12. 00 00 Although the TZ command is most commonly used to null an output to zero it may be used to offset the output to any specified value Assume that with the previously nulled system we performed this command Command 1TZ 00100 00 Response The new data output with no signal applied would be Command 1RD Response 00100 00 The output is now offset by 100 The offset value stored by the TZ command is stored in nonvolatile memory and may be read back with the Read Zero RZ command and cleared with the Clear Zero CZ command Write Enable WE Each module is write protected against accidental changing of setup or span and zero trims To change any of these write protected parameters the WE command must precede the write protected command The response to the WE command is an asterisk indicating that the module is ready to accept a write protected command After the write protected command is successfully completed the module becomes automatically write disabled Each write protected command must be preceded individually with a WE command For example Command 1WE Response Command 1WE Response 1WEF7 If a module is write enabled and the execution of a command results in an error message other than WRITE PROTECTED the module will remain write enabled until a command is successfully completed resulting in an prompt This allows the user to correct the command error without having to execute another
13. 00 00 01832 00 D533X 17 816mV 00350 00 00662 00 D534X 68 783mV 01000 00 01832 00 D545X 206 1 00090 00 00194 00 Appendix A ASCII Table Table of ASCII characters A and their equivalent values in Decimal D Hexadecimal Hex and Binary Claret represents Control function A D Hex Binary D Hex Binary 0 00 00000000 128 80 10000000 A 1 01 00000001 129 81 10000001 B 2 02 00000010 130 82 10000010 AC 3 03 00000011 131 83 10000011 D 4 04 00000100 132 84 10000100 ME 5 05 00000101 133 85 10000101 MF 6 06 00000110 134 86 10000110 G 7 07 00000111 135 87 10000111 MH 8 08 00001000 136 88 10001000 9 09 00001001 137 89 10001001 AJ 10 OA 00001010 138 8A 10001010 K 11 OB 00001011 139 8B 10001011 AL 12 OC 00001100 140 8C 10001100 AM 13 OD 00001101 141 8D 10001101 N 14 OE 00001110 142 8E 10001110 MO 15 OF 00001111 143 8 F 10001111 AP 16 10 00010000 144 90 10010000 Q 17 11 00010001 145 91 10010001 R 18 12 00010010 146 92 10010010 S 19 13 00010011 147 93 10010011 AT 20 14 00010100 148 94 10010100 MU 21 15 00010101 149 95 10010101 AV 22 16 00010110 150 96 10010110 AW 23 17 00010111 151 97 10010111 AX 24 18 00011000 152 98 10011000 AY 25 19 00011001 153 99 10011001 NZ 26 1A 00011010 154 9A 10011010 ST 27 1B 00011011 155 9B 10011011 M 28 1C 00011100 156 9C 10011100 AJ 29 1D 00011101 157 9D 10011101 DAS 130 1E 00011110 158 9E 10011110 ea o 1F 00011111 159 9F 10011111 32 20 00100000 160 AO 10100000 33 21 00100001 161 A
14. 1 10100001 E 34 22 00100010 162 A2 10100010 A D Hex Binary D Hex Binary 35 23 00100011 163 A3 10100011 36 24 00100100 164 A4 10100100 37 25 00100101 165 A5 10100101 amp 38 26 00100110 166 A6 10100110 i 39 27 00100111 167 A7 10100111 40 28 00101000 168 A8 10101000 41 29 00101001 169 A9 10101001 42 2A 00101010 170 AA 10101010 43 2B 00101011 171 AB 10101011 44 2C 00101100 172 AC 10101100 45 2D 00101101 173 AD 10101101 46 2E 00101110 174 AE 10101110 47 2F 00101111 175 AF 10101111 0 48 30 00110000 176 BO 10110000 1 49 31 00110001 177 B1 10110001 2 50 32 00110010 178 B2 10110010 3 51 33 00110011 179 B3 10110011 4 52 34 00110100 180 B4 10110100 5 53 35 00110101 181 B5 10110101 6 54 36 00110110 182 B6 10110110 7 55 37 00110111 183 B7 10110111 8 56 38 00111000 184 B8 10111000 9 57 39 00111001 185 B9 10111001 i 58 3A 00111010 186 BA 10111010 i 99 3B 00111011 187 BB 10111011 lt 60 3C 00111100 188 BC 10111100 61 3D 00111101 189 BD 10111101 gt 62 3E 00111110 190 BE 10111110 63 3F 00111111 191 BF 10111111 64 40 01000000 192 CO 11000000 A 65 41 01000001 193 C1 11000001 B 66 42 01000010 194 C2 11000010 C 67 43 01000011 195 C3 11000011 D 68 44 01000100 196 C4 11000100 E 69 45 01000101 197 C5 11000101 F 70 46 01000110 198 C6 11000110 G 71 47 01000111 199 C7 11000111 H 72 48 01001000 200 C8 11001000 73 49 01001001 201 C9 11001001 J 74 4A 01001010 202 CA 11001010 K 75 4B 01001011 203 CB 11001011
15. 2 SECOND TIME CONSTANT 64 SECOND TIME CONSTANT 3 3ce000 a 2 ODO A O O 1a 0a 04 03 GO anaaaCcfCoco 1d DD OC GB 1a 21a OA OaAO Setup Hints Until you become completely familiar with the SetUp command the best method of changing setups is to change one parameter at a time and to verify that the change has been made correctly Attempting to modify all the setups at once can often lead to confusion If you reach a state of total confusion the best recourse is to reload the factory setup shown in Table 5 5 and try again changing one parameter at a time Use the Read Setup RS command to examine the setup information currently in the module as a basis for creating a new setup For example Assume you have a D5111 unit and you wish to set the unit to echo so that it may be used in a daisy chain See Communications Read out the current setup with the Read Setup command Command 1RS Response 310701C2 By referring to Table 5 3 we find that the echo is controlled by bit 2 of byte 3 From the RS command we see that byte 3 is currently set to 01 This is the hexadecimal representation of binary 0000 0001 To set echo bit 2 must be set to 1 This results in binary 0000 0101 The new hexadecimal value of byte 3 is 05 To perform the SU command use the data read out with the RS command changing only byte 3 Command 1WE SU is write protected Response z Command 1SU310705C2 Response Verify that the modu
16. C Port Chapter 2 Functional Description A functional diagram of a typical module is shown in Figure 2 1 It is a useful reference that shows the data path in the module and to explain the function of many of the module s commands The first step is to acquire the sensor signal and convert it to digital data In Figure 2 1 all the signal conditioning circuitry has been lumped into one block the analog digital converter A D Autozero and autocalibration is performed internally and is transparent to the user The full scale output of each channel may be trimmed using the Trim Span TS command The TS command adjusts the calibration values for each channel that stored in the internal EEPROM The TS command should only be used to trim the accuracy of the unit with a laboratory standard reference applied to the sensor input The trimmed data flows into either of two digital filters The filter selection is performed automatically by the microprocessor after every A D conversion The filter selection depends on the difference of the current A D output data and the previous data stored in the output data register If the least significant decimal digit from the A D differs from the old output data by more than 10 counts the large signal filter is selected If the change is less than 10 counts the small signal filter is used The two filter system allows for different degrees of filtering depending on the rate of the input change For stead
17. D5000 SERIES USERS MANUAL REVISED 8 1 13 DGH CORPORATION P O BOX 5638 MANCHESTER NH 03108 TELEPHONE 603 622 0452 FAX 603 622 0487 URL http www dghcorp com The information in this publication has been carefully checked and is believed to be accurate however no responsibility is assumed for possible inaccuracies or omissions Applications information in this manual is in tended as suggestions for possible use of the products and not as explicit performance in a specific application Specifications may be subject to change without notice D5000 modules are not intrinsically safe devices and should not be used in an explosive environment unless enclosed in approved explosion proof housings Warranty CHAPTER 1 CHAPTER 2 CHAPTER 3 CHAPTER 4 CHAPTER 5 CHAPTER 6 CHAPTER 7 CHAPTER 8 CHAPTER 9 Appendix A Appendix B Appendix C TABLE OF CONTENTS 4 Getting Started Default Mode 1 1 Quick Hook Up 1 2 Functional Description Block Diagram 2 2 Communications Data Format 3 2 RS 232 3 2 Multi party Connection 3 3 Software Considerations 3 4 Changing Baud Rate 3 5 Using a Daisy Chain With a Dumb Terminal 3 5 RS 485 3 6 RS 485 Multidrop System 3 8 Command Set Table of Commands 4 6 User Commands 4 6 Error Messages 4 14 Setup Information and Command Command Syntax 5 1 Setup Hints 5 11 Power Supply Troubleshooting Calibration Extended Addressing ASCII TABLE D5000 Specifications Factory V
18. RROR to every command Characters in each response message appear as graphics characters RS 232 Module response message preceded by lt NULL gt character e RS 232 Module is not responding to commands 1 Using a voltmeter measure the power supply voltage at the Vs and GND terminals to verify the power supply voltage is constantly between 10 and 30Vdc 2 Verify using an ohmmeter that there are no breaks in the communications data lines 3 Connect the module to the host computer and power up each device module and computer then using a voltmeter measure the voltage be tween RECEIVE and GND This voltage should be approximately 10Vdc Repeat the measurement between TRANSMIT and GND terminals and confirm the voltage value to be approximately 10Vdc If either of the two readings is approximately 0 0Vdc then the communications data lines are wired backwards Proper communications levels on both TRANSMIT and RECEIVE terminals should idle at 10Vdc 4 Ifyou are using a serial communications converter A1000 ensure that the communications Baud Rate switch is set to the proper Baud Rate value 5 Confirm software communications settings in Host computer match those values being used by the connected module s 6 Ifthe Baud Rate value being used in the application is greater than 300 Baud and the module will only communicate 300 Baud then make sure that the DEFAULT terminal is not connected to Ground GND 7 If the module s are
19. acters signs or decimal points missing or in the wrong place Table 4 1 lists the correct syntax for all the commands VALUE ERROR This error results when an incorrect character is used as a numerical value Data values can only contain decimal digits 0 9 Hex values used in the SetUp SU can range from 0 F WRITE PROTECTED All commands that write data into nonvolatile memory are write protected to prevent accidental erasures These commands must be preceded with a Write Enable WE command or else a WRITE PROTECTED error will result Chapter 5 Setup Information SetUp Command The D5000 modules feature a wide choice of user configurable options which gives them the flexibility to operate on virtually any computer or terminal based system The user options include a choice of baud rate parity address and many other parameters The particular choice of options for a module is referred to as the setup information The setup information is loaded into the module using the SetUp SU command The SU command stores 4 bytes 32 bits of setup information into a nonvolatile memory contained in the module Once the information is stored the module can be powered down indefinitely 10 years minimum without losing the setup data The nonvolatile memory is implemented with EEPROM so there are no batteries to replace The EEPROM has many advantages over DIP switches or jumpers normally used for option selection The module never has to be opene
20. al disturbances Once a reset command is received the module will recalibrate itself The calibration process takes approximately 3 seconds For example Command 1RR Response Command 1RR Response 1RRFF Any commands sent to the module during the self calibration sequence will result ina NOT READY error Read Setup RS The read setup command reads back the setup information loaded into the module s nonvolatile memory with the SetUp SU command The response to the RS command is four bytes of information formatted as eight hex characters Command 1RS Response 31070142 Command 1RS Response 1RS3107014292 The response contains the module s channel address baud rate and other parameters Refer to the setup command SU and Chapter 5 for a list of parameters in the setup information When reading the setup with a checksum be sure not to confuse the checksum with the setup information Read Zero RZ The Read Zero command reads back the value stored in the Output Offset Register Command 1RZ Response 00000 00 Command 1RZ Response 1RZ 00000 00B0 The data read back from the Output Offset Register may be interpreted in several ways The commands that affect this value are Trim Zero TZ and Clear Zero CZ Setup Command SU Each D5000 module contains an EEPROM Electrically Erasable Program mable Read Only Memory which is used to store module setup information such as address bau
21. alues Chapter 1 Getting Started Default Mode All D5000 modules contain an EEPROM Electrically Erasable Program mable Read Only Memory to store setup information and calibration constants The EEPROM replaces the usual array of switches and pots necessary to specify baud rate address parity etc The memory is nonvolatile which means that the information is retained even if power is removed No batteries are used so it is never necessary to open the module case The EEPROM provides tremendous system flexibility since all of the module s setup parameters may be configured remotely through the com munications port without having to physically change switch and pot settings There is one minor drawback in using EEPROM instead of switches there is no visual indication of the setup information in the module It is impossible to tell just by looking at the module what the baud rate address parity and other settings are It is difficult to establish communica tions with a module whose address and baud rate are unknown To overcome this each module has an input pin labeled DEFAULT By connecting this pin to Ground the module is put ina known communications setup called Default Mode The Default Mode setup is 300 baud one start bit eight data bits one stop bit no parity any address is recognized Grounding the DEFAULT pin does not change any of the setups stored in EEPROM The setup may be read back with the Read Setup RS comma
22. at can be loaded with the SU command Take care not to assign channel 0 values within three values of an illegal address value as the microprocessor automatically assigns the next three consecutive vales to the channel 0 value It is highly recommended that only ASCII codes for printable characters be used 21 to 7E which greatly simplifies system debugging with a dumb terminal Refer to Appen dix A for a list of ASCII codes Table 5 1 lists the printable ASCII codes that may be used as addresses Table 5 1 Byte 1 ASCII Printable Characters HEX ASCII HEX ASCII HEX ASCII HEX ASCII 21 3A 51 Q 68 h R s T U V W X Y Z A VOZESBFACT TOAMMOIONWDFEnV i as IwTONS KEK eCFTHFTATOS ZT KT OONODaAARWNH O Byte 2 Byte 2 is used to configure some of the characteristics of the communica tions channel linefeeds parity and baud rate Linefeeds The most significant bit of byte 2 bit 7 controls linefeed generation by the module This option can be useful when using the module with a dumb terminal All responses from the D5000 are terminated with a carriage return ASCII 0D Most terminals will generate an automatic linefeed when a carriage return is detected However for terminals that do not have this capability the D5000 module can generate the linefeed if desired By setting bit 7 to 1 the module will send a linefeed ASCII 0A before and after each response If bit 7 is cleared 0 no linefeeds are t
23. ate value in the offset register The offset register data is nonvolatile The output data may be read with the Read Data RD command P a Cc o ra m a o 13910104 14LON SLINY LEMOJ MOLLY AE TY d1L14 44114 TeNOI5 30611 T NOIS TIF LAS S NYHHOJ Fai Z 6 6X weeg A2018 L Z aunBn4 m Chapter 3 Communications Introduction The D5000 modules have been carefully designed to be easy to interface to all popular computers and terminals All communications to and from the modules are performed with printable ASCII characters This allows the information to be processed with string functions common to most high level languages such as BASIC For computers that support RS 232C no special machine language software drivers are necessary for operation The modules can be connected to auto answer modems for long distance operation without the need for a supervisory computer The ASCII format makes system debugging easy with a dumb terminal This system allows multiple modules to be connected to a communications port with a single 4 wire cable Up to 30 RS 485 modules may be strung together on one cable A practical limit for RS 232C units is about ten although a string of 30 units is possible Extended Addressing Mode allows many more modules to be connected into high channel count systems Refer to Extended Addressing Mode in Chapter 9 The modules communicate with the host on a polling system that is ea
24. cessary to ensure that communica tions to the module is not accidently lost This is very important when changing the baud rate of an RS 232C string For more information on changing baud rate refer to Chapter 3 Let s run through an example of changing the baud rate Assume our sample module contains the setup data value of 31070080 Byte 2 is 07 By referring to the SU command chart we can determine that the module is set for no linefeeds no parity and baud rate 300 If we perform the Read Setup command with this module we would get Command 1RS Response 31070080 Let s say we wish to change the baud rate to 9600 baud The code for 9600 baud is 0010 from Table 5 2 This would change byte 2 to 02 To perform the SU command we must first send a Write Enable command because SU is write protected Command 1WE Response j Command 1SU31020080 Response E This seguence of messages is done in 300 baud because that was the original baud rate of the module The module remains in 300 baud after this seguence We can use the Read Setup RS command to check the setup data Command 1RS Response 31020080 Notice that although the module is communicating in 300 baud the setup data indicates a baud rate of 9600 byte 2 02 To actually change the baud rate to 9600 send a Remote Reset RR command RR is write protected Command 1WE Response Command 1RR Response i Up to this
25. ch module responds to its own unique address and must be interrogated by the host A module can never initiate a communications sequence A simple command response protocol must be strictly observed to avoid communi cations collisions and data errors Communications to the D5000 modules is performed with two character ASCII command codes such as RD to Read Data from the analog input A complete description of all commands is given in the Chapter 4 A typical command response sequence would look like this Command 1RD Response 00123 00 A command response sequence is not complete until a valid response is received The host may not initiate a new command until the response from a previous command is complete Failure to observe this rule will result in communications collisions A valid response can be in one of three forms 1 a normal response indicated by a prompt 2 an error message indicated by a prompt 3 a communications time out error When a module receives a valid command it must interpret the command perform the desired function and then communicate the response back to the host Each command has an associated delay time in which the module is busy calculating the response If the host does not receive a response in an appropriate amount of time specified in Table 3 1 a communications time out error has occurred After the communications time out it is as sumed that no response data is forthcoming This
26. computers that transmit a carriage return as a carriage return linefeed string Without the delay the linefeed character may collide with the first transmitted character from the module resulting in garbled data If the host computer transmits a carriage return as a single character the delay may be set to zero to improve communications response time Chapter 4 Command Set The D5000 modules operate with a simple command response protocol to control all module functions Acommand must be transmitted to the module by the host computer or terminal before the module will respond with useful data A module can never initiate a communications sequence A variety of commands exists to exploit the full functionality of the modules A list of available commands and a sample format for each command is listed in Table 4 1 Command Structure Each command message from the host must begin with a command prompt character to signal to the modules that a command message is to follow There are four valid prompt characters a dollar sign character is used to generate a short response message from the module A short response is the minimum amount of data necessary to complete the command The second prompt character is the pound sign character which generates long responses will be covered later in this chapter The other two prompt characters left curly brace and right curly brace are part of the Extended Addressing mode described in chap
27. d instead of twice per second for four channels Disabling channels effects the digital filter see byte 4 four details This feature can also be useful in long term experiments where one or two inputs may not need to be monitored for a length of time those inputs could simply be disabled until such time as they were needed again Note that if a disabled channel in a D5000 is addressed with a valid command it will not respond S S O 0 o o o 02 na Disable CJC This function pertains only to the D5300 series of thermocouple input modules If the bit is set to 1 the Cold Junction Compensation is disabled The module calculates the temperature output with a fixed cold junction temperature of 0 degrees Celsius This setup is useful for calibrating the module or in cases where remote CJC is used Normally this bit is cleared to Celsius Fahrenheit The default scaling for temperature output modules is Celsius which is selected by making bit 3 0 To change the scaling to Fahrenheit set bit 3 to 1 All modules that do not have temperature output must have bit 3 cleared to zero The scaling factors are operative only on the sensor data HI and LO limits and setpoints must be modified by appropriate commands to reflect a scaling change see Figure 2 1 Echo When bit 2 is set to 1 the D5000 module will retransmit any characters it has received on the communications line This option is necessary to daisy chain multipl
28. d because all of the options are selected through the communications port This allows the setup to be changed at any time even though the module may be located thousands of feet away from the host computer or terminal The setup information stored in a module may be read back at any time using the Read Setup command RS The following options can be specified by the SetUp command Channel address Linefeeds Parity odd even none Baud rate 300 to 115 200 Addressing Mode Extended Normal Fahrenheit Celsius Echo Communication delay 0 6 characters Number of displayed digits Large signal filter constant Small signal filter constant Each of these options will be described in detail below For a quick look up chart on all options refer to Tables 5 1 4 Command Syntax The general format for the SetUp SU command is 1SU byte1 byte 2 byte 3 byte 4 A typical SetUp command would look like 1SU31070182 Notice that each byte is represented by its two character ASCII equivalent In this example byte 1 is described by the ASCII characters 31 which is the equivalent of binary 0011 0001 31 hex The operand of a SU command must contain exactly 8 hex 0 F characters Any deviation from this format will result ina SYNTAX ERROR The Appendix contains a convenient hex to binary conversion chart For the purposes of describing the SetUp command bit 7 refers to the highest order bit of a byte of data Bit 0
29. d rate parity etc The EEPROM is a special type of memory that will retain information even if power is removed from the module The EEPROM is used to replace the usual array of DIP switches normally used to configure electronic equipment The SetUp command is used to modify the user specified parameters contained in the EEPROM to tailor the module to your application Since the SetUp command is so important to the proper operation of a module a whole section of this manual has been devoted to its description See Chapter 5 The SU command requires an argument of eight hexadecimal digits to describe four bytes of setup information Command 1SU31070182 Response Command 1SU31070182 Response 18U3107018299 Trim Span TS The Trim Span command is the basic means of trimming the accuracy of a D5000 module The TS command loads a calibration factor into nonvolatile memory to trim the full scale output of an analog input channel The D5000 series modules contain a separate calibration span trim for each channel This command is intended only to compensate for long term drifts due to aging of the analog circuits and has a useful trim value of 10 of the nominal calibration set at the factory It is not to be used to change the basic transfer function of the module Full information on the use of the TS command may be found in Chapter 8 Command 1TS 00500 00 Response Command 1TS 00500 00 Response 1TS 00500 00B0 Caut
30. e RS 232C modules Echo is optional for systems with a single RS 232C module Bit 2 must be cleared to 0 on RS 485 models See Chapter 3 for a more complete description Delay Bits 0 and 1 specify a minimum turn around delay between a command and the module response This delay time is useful on host systems that are not fast enough to capture data from quick responding commands such as RD This is particularly true for systems that use software UART s The specified delay is added to the typical command delays listed in the Software Considerations section of Chapter 3 Each unit of delay specified by bits 0 and 1 is egual to the amount of time reguired to transmit one character with the baud rate specified in byte 2 For example one unit of delay at 300 baud is 33 3 mS for 38 4 kilobaud the delay is 0 26 mS The number of delay units is selectable from 0 to 6 as shown in Table 5 3 In some systems such as IBM BASIC a carriage return CR is always followed by a linefeed LF The D5000 modules will respond immediately after a command terminated by a CR and will ignore the linefeed To avoid a communications collision between the linefeed and the module response the module should be setup to delay by 2 units Table 5 3 Byte 3 Options CHANNEL 3 DISABLE CHANNEL 3 ENABLE CHANNEL 2 DISABLE CHANNEL 2 ENABLE CHANNEL 1 DISABLE CHANNEL 1 ENABLE CJC D5300 S NO CJC D5300 S CELSIUS FAHRENHEIT NO ECHO ECHO NO DELAYS 2 BYTE
31. e data from each channel is separated by acarriage return or carriage return and line feed if lines feed is enabled used as a delimiter This command can be very useful in spreadsheet applications In order to properly parse the data values from each channel the Read Block command returns an asterisk followed by a carriage return as response message for any disabled channel s The asterisk response message applies to both same the long form and short form prompts Command 1RB Response 00072 00 00123 00 78900 00 00072 00 Command 1RB Response 1RB 00072 10A2 2RB 00123 009F 3RB 78900 00B2 4RB 00072 00A6 Read Data RD The Read Data command is the basic command used to read the buffered sensor data The output buffer Figure 2 1 allows the data to be read immediately without waiting for an input A D conversion For example Command 1RD Response 00072 00 Command 1RD Response 1RD 00072 10A4 Since the RD command is the most frequently used command in normal operation a special shortened version of the command is available If a module is addressed without a two letter command the module interprets the string as an RD command Command 1 Response 00072 10 Command 1 Response 1RD 00072 10A4 Read Extended Address REA The Read Extended Address is used to read back two character address stored by the Extended Address EA command The response message is four characters representin
32. er hex digits of the sum are A4 which agrees with the transmitted checksum The transmitted checksum is the character string equivalent to the calcu lated hex integer The variables must be converted to like types in the host software to determine equivalency If checksums do not agree a communications error has occurred If a module is setup to provide linefeeds the linefeed characters are not included in the checksum calculation Parity bits are never included in the checksum calculation Table 4 1 D5000 Command Set Command and Definition Typical Typical Command Response Message Message prompt RB Read Block of data 1RB 00072 00 00836 00 01234 00 00932 00 RD Read Data 1RD 00072 00 REA Read Extended Address 1REA 3031 RID Read IDentification 1RID BOILER RMN Read displayed MiNimum 1RMN 00100 00 RMX Read displayed MaXimum 1RMX 00025 00 RS Read Setup 1RS 31070142 RZ Read Zero 1RZ 00000 00 WE Write Enable 1WE 7 Write Protected Commands CZ Clear Zero 1CZ i ID IDentification 1IDBOILER ROOM RR Remote Reset 1RR SU Setup Module 1SU31070142 i TS Trim Span 1TS 00600 00 ig TZ Trim Zero 1TZ 00000 00 K WEA Write Extended Address 1WEA3031 id WMN Write displayed MiNimum 1WMN A WMX Write displayed MaXimum 1WMX jE D5000 User Commands Note that in all command and response examples given below a carriage return is implied after every character string Clear Zero
33. error usually results when an improper command prompt or address is transmitted The table below lists the timeout specification for each command Mnemonic Timeout RD 10 mS All other commands 100 mS Table 3 1 Response Timeout Specifications The timeout specification is the turn around time from the receipt of a command to when the module starts to transmit a response Data Format All modules communicate in standard NRZ asynchronous data for mat This format provides one start bit seven data bits one parity bit and one stop bit for each character RS 232C RS 232C is the most widely used communications standard for information transfer between computing equipment RS 232C versions of the D5000 will interface to virtually all popular computers without any additional hardware Although the RS 232C standard is designed to connect a single piece of equipment to a computer the D5000 system allows for several modules to be connected in a daisy chain network structure The advantages offered by the RS 232C standard are 1 widely used by all computing equipment 2 no additional interface hardware in most cases 3 separate transmit and receive lines ease debugging 4 compatible with dumb terminals However RS 232C suffers from several disadvantages 1 low noise immunity 2 short usable distance 3 greater communications delay in multiple module systems 4 less reliable loss of one module communications are lost 5 wiring is sli
34. g the hex ASCII codes for the two character address Command 1REA Response 3031 Command 1REA Response 1REA3031FA In this example the 30 and 31 are the hex ASCII codes for the characters and 1 respectively The Extended Address is 01 Read IDentification RID The Read Identification RID command is used to read data previously stored by the ID command The RID command response message length is variable depending on the stored message length The maximum re sponse length can be up to 25 characters using the long form prompt and linefeeds enabled Command 1RID Response BOILER ROOM Command 1RID Response 1RIDBOILER ROOM54 Read MaXimum RMX The Read MaXimum RMX command reads the displayed output value corresponding to analog input full scale The full scale displayed data value may be changed by using the WMX command Command 1RMX Response 00020 00 Command 1RMX Response 1RMX 00020 00FD Read MiNimum RMN The Read MiNimum RMN command reads the displayed output value corresponding to the analog input full scale The full scale displayed data value may be changed with the WMN command Command 1RMN Response 00000 00 Command 1RMN Response 1 RMN 00000 00F 1 Remote Reset RR The reset command allows the host to perform a program reset on the module s microprocessor This may be necessary if the module s internal program is disrupted by static or other electric
35. ghtly more complex than RS 485 6 host software must handle echo characters Single Module Connection Figure 1 1 shows the connections necessary to attach one module to a host Use the Default Mode to enter the desired address baud rate and other setups see Setups The use of echo is not necessary when using a single module on the communications line Multi party Connection RS 232C is not designed to be used in a multiparty system however the D5000 modules can be daisy chained to allow many modules to be connected to a single communications port The wiring necessary to create the daisy chain is shown in Figure 3 1 Notice that starting with the host each Transmit output is wired to the Receive input of the next module in the daisy chain This wiring sequence must be followed until the output of the last module in the chain is wired to the Receive input of the host All modules in the chain must be setup to the same baud rate and must echo all received data see Setups Each module must be setup with its own unique address to avoid communications collisions see Setups In this network any characters transmitted by the host are received by each module in the chain and passed on to the next station until the information is echoed back to the Receive input of the host In this manner all the commands given by the host are examined by every module If a module in the chain is correctly addressed and receives a valid command it will respond b
36. he module responds with a long form response This type of response will echo the command message supply the necessary response data and will add a two character checksum to the end of the message Long form responses are used when the host wishes to verify the command received by the module The checksum is included to verify the integrity of the response data The command prompt may be used with any command For example Command 1RD short form Response 00072 10 Command 1RD long form Response 1RD 00072 10A4 A4 checksum Checksum Checksum is a two character hexadecimal value appended to the end of a message It verifies that the message received is exactly the same as the message sent The checksum ensures the integrity of the information communicated Command Checksum A two character cumulative checksum may be appended to any command transmitted to the module as a user option When a module interprets a command it looks for the two extra characters and assumes that it is a checksum If the checksum is not present the module will perform the command normally If the two extra characters are present the module calculates the checksum for the message If the calculated checksum does not agree with the transmitted checksum the module responds with a BAD CHECKSUM error message and the command is aborted If the checksums agree the command is executed If the module receives a single extra character it respo
37. ion TS is the only command associated with the span trim There is no provision to read back or clear errors loaded by the TS command Misuse of the TS command may destroy the calibration of the unit which can only be restored by using laboratory calibration instruments in a controlled environment An input signal must be applied when using this command Trim Zero TZ The Trim Zero command is used to load a value into a channel Output Offset Register and null out an offset errors in the output data Each D5000 series module contains four output offset registers Specify the correct channel address in the command string for trim values to be loaded into the proper output offset register and trim offsets created by sensors It may also be used to null out data to create a deviation output Example Assume a D5111 voltage input module is being used and an initial reading with no input signal applied reveals an initial offset error Command 1RD Response 00005 00 With no signal applied trim the output to read zero To trim use the TZ command and specify the desired output reading Command 1TZ 00000 00 zero output Response The TZ command will load a data value into the Output Offset Register to force the output to read zero The module will compensate for any previous value loaded into the Output Offset Register If another output reading is taken it will show that the offset has been eliminated Command 1RD Response 000
38. l A dumb terminal can be used to communicate to a daisy chained system The terminal is connected in the same manner as a computer used as a host Any commands typed into the dumb terminal will be echoed by the daisy chain To avoid double characters when typing commands set the terminal to full duplex mode or turn off the local echo The daisy chain will provide the input command echo RS 485 RS 485 is a recently developed communications standard to satisfy the need for multidropped systems that can communicate at high data rates over long distances RS 485 is similar to RS 422 in that it uses a balanced differential pair of wires switching from 0 to 5V to communicate data RS 485 receivers can handle common mode voltages from 7V to 12V without loss of data making them ideal for transmission over great distances RS 485 differs from RS 422 by using one balanced pair of wires for both transmitting and receiving Since an RS 485 system cannot transmit and receive at the same time it is inherently a half duplex system RS 485 offers many advantages over RS 232C 1 balanced line gives excellent noise immunity 2 can communicate with D5000 modules at 115200 baud 3 communications distances up to 4 000 feet 4 true multidrop modules are connected in parallel 5 can disconnect modules without losing communications 6 up to 30 modules on one line or up to 3721 using Extended Address Mode and RS 485 repeaters 7 no communications delay due
39. l filter If the result of the most recent A D conversion differs from the last output value by less than ten counts of the last displayed digit the small signal time constant is used Le s look at an example The D5451 thermistor module has been changed from a standard resolution of 0 01 degrees to an output resolution of 0 1 degrees The number of displayed digits setup for this module is now 6 digits from byte 4 of the setup data Therefore the large signal filter will be selected if a new input conversion differs from the previous value by gt 1 0 degree Previous data New data Filter selected 00098 00 00098 50 small 00098 00 00099 50 large 00099 00 00099 90 small 00099 00 00097 90 large 00050 50 00050 00 small 00050 50 00060 00 small If the number of displayed digits is changed to reduce output resolution filter selection is also affected If the number of displayed digits in the previous example is changed to 5 the output resolution becomes 1 0 degree In this case the large signal time constant is used if the new reading differs from the old by more than 10 0 degrees Previous data New data Filter selected 00090 00 00095 00 small 00089 00 00100 00 large 00090 00 00091 00 small 00090 00 00075 00 large 00050 00 00045 00 small 00050 00 00039 00 large Large Signal Time Constant The large signal filter time constant is specified by bits 3 4 5 of byte 4 It may be specified from 0 no filter to 64
40. le is echoing characters and the setup is correct By using the RS command and changing one setup parameter at a time any problems associated with incorrect setups may be identified immediately Once a satisfactory setup has been developed record the setup value and use it to configure similar modules If you commit an error in using the SetUp command it is possible to lose communications with the module In this case it may be necessary to use the Default Mode to re establish communications Table 5 5 Factory Setups by Model All modules from the factory are set for address 1 300 baud no parity Model Setup Message D511X D515X D525X 3107E1C2 D512X 3107E182 D513X D514X 3107E142 D53XX 3107E142 D545X 3107E1C2 Chapter 6 Power Supply D5000 modules may be powered with an unregulated 10 to 30Vdc Power supply ripple must be limited to 5V peak to peak and the instanta neous ripple voltage must be maintained between the 10 and 30 volt limits at all times The modules contain a low voltage detection circuit that shuts down all circuits in the module at approximately 9 5 Vdc All power supply specifications are referred to the module connector the effects of line voltage drops must be considered when the module is powered remotely All D5000 modules employ an on board switching regulator to maintain good efficiency over the 10 to 30 volt input range therefore the actual current draw is inversely proportional to the line
41. le module connected to a terminal or computer for the purpose of identifying and modifying setup values In most cases a module in Default Mode may not be used in a string with other modules RS 232 amp RS 485 Quick Hook Up Software is not required to begin using your D5000 module We recommend that you begin to get familiar with the module by setting it up on the bench Start by using a dumb terminal or a computer that acts like a dumb terminal Make the connections shown in the quick hook up drawings Figures 1 1 or 1 2 Put the module in the Default Mode by grounding the Default terminal Initialize the terminal communications package on your computer to put it into the terminal mode Since this step varies from computer to computer refer to your computer manual for instructions Begin by typing 1RD and pressing the Enter or Return key The module will respond with an followed by the data reading at the input The data includes sign seven digits and a decimal point For example if you are using a thermocouple module and measuring room temperature your reading might be 00025 00 The temperature reading will initially be in C which has D5121 VOLTAGE Mule if Hsing a 06 25 connector ground Iz ted ro pln T Fin 3 Is rled ro TRANSMIT And pin 2 is tied ta RECFIYF nn the madula Figure 1 1 RS 232C Quick Hook Up D5122 VOLTAGE R 485 0425 Figure 1 2 RS 485 Quick Hook Up been preset at the fac
42. ll not echo any characters that appear on its receive input However if a character is received during this computation period it will be stored in the module s internal receive buffer This character will be echoed after the response string is transmitted by the module This situation will occur if the host computer appends a linefeed character on the command carriage return In this case the linefeed character will be echoed after the response string has been transmitted The daisy chain also affects the command timeout specifications When a module in the chain receives a character it is echoed by retransmitting the character through the module s internal UART This method is used to provide more reliable communications since the UART eliminates any slewing errors caused by the transmission lines However this method creates a delay in propagating the character through the chain The delay is equal to the time necessary to retransmit one character using the baud rate setup in the module Baud Rate Delay Baud Rate Delay 300 33 30ms 9600 1 04ms 600 16 70ms 19200 0 52ms 1200 8 33ms 38400 0 26ms 2400 4 17ms 57600 173 6 s 4800 2 08ms 115200 86 8 s One delay time is accumulated for each module in the chain For example if four modules are used in a chain operating at 1200 baud the accumulated delay time is 4 X 8 33 mS 33 3 mS This time must be added to the times listed in Table 3 1 to calculate the correct communications time out er
43. lter Bits 3 4 5 Small Signal Filter Bits 0 1 2 The modules contain a versatile single pole low pass digital filter to smooth out unwanted noise caused by interference or small signal variations The digital filter offers many advantages over traditional analog filters The filtering action is done completely in firmware and is not affected by component drifts offsets and circuit noise typically found in analog filters The filter time constant is programmable through the SetUp SU command and can be changed at any time even if the module is remote from the host The digital filter features separate time constants for large and small signal variations The Large Signal Filter time constant is controlled by bits 3 4 5 This time constant is used when large signal variations are present on the input The Small Signal Filter time constant is controlled by bits 0 1 2 This filter time constant is automatically selected when input signal variations are small The microprocessor in the module automatically selects the correct filter constant after every A D conversion The constant selected depends on the magnitude of the change of the input signal and the setup for the number of digits displayed The microprocessor always keeps the value of the last calculated output to compare to a new data conversion If the new data differs from the last output by more than ten counts of the last displayed digit the large signal time constant is used in the digita
44. n this particular case remains unchanged To change the module base channel address to 2 byte 1 of the SetUp command becomes 32 which is the ASCII code for the character 2 Now the command will look like this 1SU32070080 When this command is sent the module base channel address is changed from 1 to 2 and will no longer respond to address 1 Keep record of module addresses in order to avoid overlaps in channel addressing When using the SU command to change the address of a module be sure to record the new address in a place that is easily retrievable The only way to communicate with a module with an unknown address is with the Default Mode Note that when communicating with aD5000 module in Default Mode the module will respond with the address value of channel 0 unless the channel was properly addressed Therefore if address a is sent to a module in default mode that is addressed as 0 thru 3 channel 0 data is returned But if the same module is addressed as 2 channel 2 data is returned The most significant bit of byte 1 bit 7 must be set to 0 In addition there are six ASCII codes that are illegal for use as an address to any channel These codes are 00 0D 24 23 7B 7D which are ASCII codes for the characters NUL CR and Using these codes for an address will cause an ADDRESS ERROR and the setup data will remain unchanged This leaves a total of 122 possible addresses th
45. nd to determine all of the setups stored in the module In Default Mode all commands are available Each channel of the D5000 has its own channel address and all four channels are enabled in Default Mode The addresses assigned to a module must be four consecutive ASCII values such as 0 1 2 3 A module in Default Mode will respond to any address except the six identified illegal values NULL CR A dummy address must be included in every command for proper responses The ASCII value of the module s first channel address may be read back with the RS command A properly addressed channel can read data values and can modify calibration values such as trim span in the Default Mode However it must be noted that in Default Mode a module that is addressed with any value other than the four proper address values assigned to it will always respond with the data from its first channel For example if a module as described above is addresses with any character other than 0 1 2 3 it will respond with or modify data from channel 0 Setup information in a module may be changed at will with the SetUp SU command Baud rate and parity setups may be changed without affecting the Default values of 300 baud and no parity When the DEFAULT pin is released the module automatically performs a program reset and config ures itself to the baud rate and parity stored in the setup information The Default Mode is intended to be used with a sing
46. nds with SYNTAX ERROR and the command is aborted For example Command 1RD no checksum Response 00072 10 Command 1RDEB with checksum Response 00072 10 Command 1RDAB incorrect checksum Response 1 BAD CHECKSUM Command 1RDE one extra character Response 1 SYNTAX ERROR Response Checksums If the long form version of a command is transmitted to a module a checksum will be appended to the end of the response For example Command 1RD short form Response 00072 10 Command 1RD long form Response 1RD 00072 10A4 A4 checksum Checksum Calculation The checksum is calculated by summing the hexadecimal values of all the ASCII characters in the message The lowest order two hex digits of the sum are used as the checksum These two digits are then converted to their ASCII character equivalents and appended to the message This ensures that the checksum is in the form of printable characters Example Append a checksum to the command 1RD Characters 1 R D ASCII hex values 23 31 52 44 Sum hex addition 23 31 52 44 EA The checksum is EA hex Append the characters E and A to the end of the message 1RDEA Example Verify the checksum of a module response 1RD 00072 10A4 The checksum is the two characters preceding the CR A4 Add the remaining character values x 1 R D 0 0 0 7 2 1 0 2A 31 52 44 2B 30 30 30 37 32 2E 31 30 A4 The two lowest ord
47. ny commands require additional data values to complete the command definition as shown in the example commands in Table 4 1 The particular data necessary for these commands is described in full in the complete command descriptions The most common type of data used in commands and responses is analog data Analog data is always represented in the same format for all models in the D5000 series Analog data is represented as a nine character string consisting of a sign five digits decimal point and two additional digits The string represents a decimal value in engineering units Examples 12345 68 00100 00 00072 10 00000 00 When using commands that require analog data as an argument the full nine character string must be used even if some digits are not significant Failure to do this results ina SYNTAX ERROR Analog data responses from the module will always be transmitted in the nine character format This greatly simplifies software parsing routines since all analog data is in the same format for all module types In many cases some of the digits in the analog data may not be significant For instance the D5300 thermocouple input modules feature 1 degree output resolution A typical analog data value from this type of module could be 00123 00 The two digits to the right of the decimal point have no significance in this particular model However the data format is always adhered to in order to maintain compatibility with other
48. ny sensor output signals are transmitted as 4 to 20mA signals The following example demonstrates scaling a 4 to 20mA signal to 0 to 100 using a D5251 or D5252 module The actual input range of these modules is 0 to 25mA to make it easier to adjust for zero and span and to allow for drift in the end points of the input Since the input range is 0 to 25mA and you want to use a portion of that range you must determine the new minimum and maximum values The two desired values 4mA 0 and 20mA 100 determine the desired transfer function Extrapolate this function to the full scale range of the module which is 0 25mA This results in endpoints at OMA 25 and 25mA 131 25 To input the new minimum and maximum values send a Write Enable command 1WE followed by a Write MiNmum displayed value com mand 1VWMN 00025 00 The response to both commands should be an Send a 1WE command followed by a Write MaXimum displayed value command 1WMX 00131 25 The response to both commands should be an The entire range for all four input channels of the module are rescaled and all values are read in percent ERROR MESSAGES The D5000 modules feature extensive error checking on input commands to avoid erroneous operation Any errors detected will result in an error message and the command will be aborted All error messages begin with followed by the channel address a space and error description The error messages have the same forma
49. ompt precedes an error message All response messages are terminated with a CR Many commands simply return a character to acknowledge that the command has been executed by the module Other commands send data information following the prompt The response format of all commands may be found in the detailed command description The maximum response message length is 20 characters A command response sequence is not complete until a valid response is received The host may not initiate a new command until the response from a previous command is complete Failure to observe this rule will result in communications collisions A valid response can be in one of three forms 1 a normal response indicated by a prompt 2 an error message indicated by a prompt 3 a communications time out error When a module receives a valid command it must interpret the command perform the desired function and communicate the response back to the host Each command has an associated delay time in which the module is busy calculating the response If the host does not receive a response in an appropriate amount of time specified in Table 3 1 a communications time out error has occurred After the communications time out it is assumed that no response data is forthcoming This error usually results when an improper command prompt or address is transmitted Long Form Responses When the pound sign command prompt is used t
50. point all communications have been sent at 300 baud The module will not respond to any further communications at 300 baud because it is now running at 9600 baud At this point the host computer or terminal must be set to 9600 baud to continue operation If the module does not respond to the new baud rate most likely the setup data is incorrect Try various baud rates from the host until the module responds The last resort is to set the module to Default Mode where the baud rate is always 300 Setting a string of RS 232C modules to a new baud rate requires special consideration Refer to Chapter 3 for instructions Bit 4 Bit 4 is used to enable or disable extended addressing mode Table 5 2 Byte 2 Linefeed Parity Addressing and Baud Rate FUNCTION DATABIT 0 md 85 A LINEFEED NO LINEFEED NO PARITY NO PARITY EVEN PARITY ODD PARITY NORMAL ADDRESSING EXTENDED ADDRESSING 115200 BAUD 57600 BAUD 38400 BAUD 19200 BAUD 9600 BAUD 4800 BAUD 2400 BAUD 1200 BAUD 600 BAUD 300 BAUD Byte 3 The default value for this byte is 01 Channel Enable Disable Input channels may be enabled and disabled at will by using the SetUp command The factory setting for the D5000 series is all four channels enabled However the user can choose to disable one to three unnecessary channels channel 0 is always enabled Disabling channels increases the sampling rate for example two channels sample at four times per secon
51. ransmitted tH When using the command prompt the linefeed characters are not included in the checksum calculation Parity Bits 5 and 6 select the parity to be used by the module Bit 5 turns the parity on and off If bit 5 is 0 the parity of the command string is ignored and the parity bit of characters transmitted by the module is set to 1 If bit 5 is 1 the parity of command strings is checked and the parity of characters output by the module is calculated as specified by bit 6 If bit 6 is parity is even if bit 6 is 1 parity is odd If a parity error is detected by the module it will respond with a PARITY ERROR message This is usually caused by noise on the communications line If parity setup values are changed with the SU command the response to the SU command will be transmitted with the old parity setup The new parity setup becomes effective immediately after the response message from the SU command Baud Rate Bits 0 3 specify the communications baud rate The baud rate can be selected from ten values between 300 and 115200 baud Refer to Table 5 2 for the desired code The baud rate selection is the only setup data that is not implemented directly after an SU command In order for the baud rate to be actually changed a module reset must occur A reset is performed by sending a Remote Reset RR command see Communications or powering down This extra level of write protection is ne
52. responds to the applied input no calibration is necessary If the output is in overload check the circuit connections or use a different input value to obtain an output within the operating range of the module To trim the output use the Trim Span TS command The argument of the TS command should correspond to the desired module output After performing the TS command verify the trim with the RD command For example to trim a channel in a D5121 module 1 Clear the output offset register Command 1WE Response 7 CZ is write protected Command 1CZ Response 2 Apply an input voltage near 90 of rated full scale In this case we will use a 900mV input voltage that is accurate to at least 0 02 Obtain an output reading Command 1RD Response 00900 30 In this case the output of the module is off by 300LIV To trim Command 1WE Response a TS is write protected Command 1TS 00900 00 Response x This sequence will trim the output to 00900 00 Verify Command 1RD Response 00900 00 This same procedure should be repeated for all four channels in the module The calibration procedure is complete when all four channels have been calibrated Table 9 1 Calibration Values Model Input Stimulus Output Data F D511X 90mV 00090 00 D512X 900mV 00900 00 D513X 4 5V 04500 00 D514X 9V 09000 00 D515X 90V 00090 00 D525X 20mA 00020 00 D531X 39 13mV 00700 00 01292 00 D532X 41 269mV 010
53. ror For modules with RS 232C outputs the programmed communications delay specified in the setup data see Chapter 5 is implemented by sending a NULL character 00 followed by an idle line condition for one character time This results in a delay of two character periods For longer delay times specified in the setup data this sequence is repeated Programmed communications delay is seldom necessary in an RS 232C daisy chain since each module in the chain adds one character of communications delay Changing Baud Rate Itis possible to change the baud rate of an RS 232C daisy chain on line This process must be done carefully to avoid breaking the communications link 1 Use the SetUp SU command to change the baud rate setup on each module in the chain Be careful not to generate a reset during this process A reset can be caused by the Remote Reset RR command or power interruptions 2 Verify that all the modules in the chain contain the new baud rate setup using the Read Setup RS command Every module in the chain must be setup for the same baud rate 3 Remove power from all the modules for at least 10 seconds Restore power to the modules This generates a power up reset in each module and loads in the new baud rate 4 Change the host baud rate to the new value and check communica tions 5 Be sure to compensate for a different communications delay as a result of the new baud rate Using A Daisy Chain With A Dumb Termina
54. s in each response message appear as graphics characters 1 Set the communications software parity setting to M for MARK parity type and 7 data bits Or utilize any parity type in both the module and software other than NO parity 2 In custom written software routines mask off the most significant bit of each received character to logic 0 Thus forcing the received character to 7 bit ASCII value e RS 232 Module response message preceded by lt NULL gt character Set Delay value to NO DELAYS in setup message Chapter 8 Calibration The D5000 module is initially calibrated at the factory and has a recom mended calibration interval of one year Separate calibration constants for each channelare stored in the EEPROM and may be trimmed using the Trim Span TS and Trim Zero TZ commands There are no pots to adjust Calibration procedure is as follows Voltage and current inputs clear the output offset register using the Clear Zero CZ command Zero trims are not necessary due to the built in auto zero function Apply a Known calibrated voltage or current to the input of the module The calibrated stimulus should be adjusted to be near 90 of the full scale output of the modules for best results Obviously the accuracy of the calibrated voltage or current must be better than the rated accuracy of the module which in most cases is 0 02 of full scale Use the Read Data RD command to obtain an output reading If the output cor
55. seconds The time constant for a first order filter is the time required for the output to reach 63 of its final value for a step input Small Signal Time Constant Bits 0 1 2 specify the filter time constant for small signals Its values are similar to the ones for the large signal filter Most sensors can benefit from a small amount of small signal filtering such as T 1 second In most applications the small signal time constant should be larger than the large signal time constant This gives stable readings for steady state inputs while providing fast response to large signal changes Disabled channels and filtering time constants Disabling channels will change the digital filter time constants the table below describes the changes Large and Small Signal Channels Enabled Filter Time Constants 1 2 3 4 0 0 0 0 0 1 25 5 65 1 2 5 1 1 3 2 3 1 2 2 6 4 4 2 4 5 2 8 5 4 8 10 4 16 6 8 16 20 8 32 7 16 32 416 64 Table 5 4 Byte 4 Displayed Digits and Filter Time Constants FUNCTION XXXX0 00 DISPLAYED DIGITS XXXXX 00 DISPLAYED DIGITS XXXXX X0 DISPLAYED DIGITS XXXXX XX DISPLAYED DIGITS NO LARGE SIGNAL FILTERING 1 SECOND TIME CONSTANT 2 SECOND TIME CONSTANT 4 SECOND TIME CONSTANT 8 SECOND TIME CONSTANT 16 SECOND TIME CONSTANT 32 SECOND TIME CONSTANT 64 SECOND TIME CONSTANT NO SMALL SIGNAL FILTERING 1 SECOND TIME CONSTANT 2 SECOND TIME CONSTANT 4 SECOND TIME CONSTANT 8 SECOND TIME CONSTANT 16 SECOND TIME CONSTANT 3
56. sistance effect lt 20 uV per 3500 e Open thermocouple indication e Input burnout protection to 250Vac e User selectable C or F e Overrange indication e Automatic cold junction compensation and linearization D5450 Thermistor Inputs e Thermistor types 22520 at 25 C e Range 0 C to 100 C e Resolution 0 01 C or F e Accuracy 0 1 C Common mode rejection 100dB at 50 60Hz Input protection to 30Vdc e User selectable C or F Appendix C Factory Values Listed below is a table of factory installed values for minimum and maximum displayed values for each model This information can be used to reinstall the factory scaling values to a module using the WMN and WMX commands see Chapter 4 Model Factory Factory Minimum Maximum Value Value 511x 00100 00 00100 00 512x 01000 00 01000 00 513x 05000 00 05000 00 514x 10000 00 10000 00 515x 00100 00 00100 00 525x 00000 00 00025 00 531x 00200 50 00760 50 532x 00150 50 01250 50 533x 00200 50 00400 50 534x 00100 00 01000 00 545x 00000 00 00100 00
57. t for either the or prompts For example 1 SYNTAX ERROR There are eight error messages and each error message begins with a different character It is easy for a computer program to identify the error without having to read the entire string ADDRESS ERROR There are six ASCII values that are illegal for use as a module address NULL 00 CR 0D 24 23 7B and 7D The ADDRESS ERROR will occur when an attempt is made to load an illegal address into a module with the SetUp SU command An attempt to load an address greater than 7F will produce an error BAD CHECKSUM This error is caused by an incorrect checksum included in the command string The module recognizes any two hex characters appended to a command string as a checksum Usually a BAD CHECKSUM error is due to noise or interference on the communications line Often repeating the command solves the problem If the error persists either the checksum is calculated incorrectly or there is a problem with the communications channel More reliable transmissions might be obtained by using a lower baud rate COMMAND ERROR This error occurs when the command is not recognized by the module Often this error results when the command is sent with lower case letters All valid commands are upper case NOT READY If a module is reset it performs a self calibration routine which takes 2 3 seconds to complete Any commands sent to the module during
58. ter 10 The prompt character must be followed by a single address character identifying the channel of the module to which the command is directed Each module attached to a common communications port must be setup with its own unique addresses so that commands may be directed to the proper unit Module addresses are assigned by the user with the SetUp SU command Printable ASCII characters such as 1 ASCII 31 or A ASCII 41 are the best choices for address characters Each D5000 module requires from one to four addresses The address character is followed by a two or three character command that identifies the function to be performed by the module All of the available commands are listed in Table 4 1 along with a short function definition All commands are described in Chapter 4 Commands must be transmitted as upper case characters A two character checksum may be appended to any command message as a user option See Checksum in Chapter 4 All commands must be terminated by a Carriage Return character ASCII 0D In all command examples in this text the Carriage Return is either implied or denoted by the symbol CR In addition to the command structure discussed above there is a special command format called Extended Addressing This mode uses a different prompt either or to distinguish it from the regular command syntax The Extended Addressing mode is described in chapter 10 Data Structure Ma
59. to multiple modules 8 simplified wiring using standard telephone cable RS 485 does have disadvantages Very few computers or terminals have built in support for this new standard Interface boards are available for the IBM PC and compatibles and other RS 485 equipment will become avail able as the standard gains popularity An RS 485 system usually requires an interface We offer the A1000 and A2000 interface converters that will convert RS 232 signals to RS 485 or repeat RS 485 signals The A1000 converters also include a 24Vdc one amp power supply for powering D5000 series modules The A1000 or A2000 connected as an RS 485 repeater can be used to extend an existing RS 485 network on one serial port Dog HOST RS 485 DS 4 GND B GROUND 416009 HLHO CA E Black R Red G Green Y Yellow Local POWER SUPPLY _ 610003 Figure 3 2A5 465 Network Up to 4 OOO Feet gt 6160 9 HLHO AJ RS 485 Multidrop System Figure 3 2 illustrates the wiring required for multiple module RS 485 sys tem Notice that every module has a direct connection to the host system Any number of modules may be unplugged without affecting the remaining modules Each module must be setup with a unique address and the addresses can be in any order All RS 485 modules must be setup for no echo to avoid bus conflicts see Setup Also note that the connector pins on each module are labeled with notations B R G
60. tory Once you have a response from the module you can turn to the Chapter 4 and get familiar with the command set All modules are shipped from the factory with a setup that includes a channel address of 1 300 baud rate no linefeeds no parity alarms off no echo and two character delay Refer to the Chapter 5 to configure the module to your application RS 485 Quick Hook up to a RS 232 port An RS 485 module may be easily interfaced to an RS 232C terminal for evaluation purposes This connection is only suitable for benchtop operation and should never be used for a permanent installation Figure 1 3 shows the hook up This connection will work provided the RS 232C transmit output is current limited to less than 50mA and the RS 232C receive threshold is greater than OV All terminals that use 1488 and 1489 style interface IC s will satisfy this requirement With this connection characters generated by the terminal will be echoed back To avoid double characters the local echo on the terminal should be turned off If the current limiting capability of the RS 232C output is uncertain insert a 1000 to 1kO resistor in series with the RS 232 output In some rare cases it may be necessary to connect the module s DATA pin to ground through a 1000 to 1kQ resistor 10 to 30 Ydc Power Supply D5122 YOLTAGEF SSSSS Ses AG Note If using a DB 25 connect or ground is tied to pin 7 Figure 1 3 RS 485 Quick Hook Up with RS 232
61. unications error checking via checksum Can be used with dumb terminal e Scan up to 250 channels per second All communications setups stored in EEPROM Power Requirements Unregulated 10V to 30Vdc 0 75W max Internal switching regulator Protected against power supply reversals Environmental Temperature Range Operating 25 C to 70 C Storage 25 C to 85 C Relative Humidity 0 to 95 noncondensing Warranty 12 months on workmanship and material D5100 Voltage Inputs e Voltage ranges 100mV 1V 5V 10V 100Vdc e Resolution 0 01 of FS 4 digits e Accuracy 0 02 of FS max Common mode rejection 100dB at 50 60Hz e Zero drift 1 count max autozero Span tempco 50ppm C max Input burnout protection to 250Vac Input impedance lt 1V input 100MO min 2 5V input 1MQ min D5200 Current Inputs e Current ranges 4 20mAdc e Resolution 0 04 of FS e Accuracy 0 04 of FS e Common mode rejection 100dB at 50 60Hz Zero drift 1 count max autozero e Span tempco 50ppm C max e Voltage drop 1 0V max D5300 Thermocouple Inputs Thermocouple types J K T E factory set e Ranges J 200 C to 760 C K 150 C to 1250 C T 200 C to 400 C 100 C to 1000 C e Resolution 1 e Overall Accuracy error from all sources from 0 to 40 C ambient 1 0 C Common mode rejection 100dB at 50 60Hz e Input impedance 100MO min e Lead re
62. voltage D5000 modules without sensor excitation consume a maximum of 75 watts and this figure should be used in determining the power supply current requirement For example assume a 24 volt power supply will be used to power four modules The total power requirement is 4 X 75 3 watts The power supply must be able to provide 3 24 0 125 amps The low voltage detection circuit shuts down the module at approximately 9 5Vdc If the module is interrogated while in a low power supply condition the module will not respond Random NOT READY error messages could indicate that the power supply voltage is periodically drooping below the 10V minimum Small systems may be powered by using wall mounted calculator type modular power supplies These units are inexpensive and may be obtained from many retail electronics outlets For best reliability modules operated on long communications lines gt 500 feet should be powered locally using small calculator type power units This eliminates the voltage drops on the Ground lead which may interfere with communications signals In this case the V terminal is connected only to the local power supply The Ground terminal must be connected back to the host Chapter 7 Troubleshooting Symptom RS 232 Module is not responding to commands RS 485 Module is not responding to commands Error in displayed value Read Data RD values are factor of two times normal values Module responds with 1 COMMAND E
63. y state signals the small signal filter averages out noise and small input changes to give a stable steady state output The large signal filter is activated by step changes or very noisy input signals The time constants for the two filters can be specified independently with the SetUp SU command The filter values are stored in nonvolatile memory Typically the small signal filter is set to a larger time constant than the large signal filter This gives very good noise rejection along with fast response to step inputs The modules allow user selectable output scaling in C or F on temperature data This selection is shown in Figure 2 1 as a switch following the digital filters The default scaling in the modules is C but this may be converted to F by feeding the data through a conversion routine The switch position is controlled by a bit in the setup data and may be changed with the SetUp SU command The scaling selection is nonvolatile In non temperature applications C should always be selected The scaled data is summed with data stored in the Output Offset Register to obtain the final output value The output offset is controlled by the user and has many purposes The data in the Output Offset Register may be used to trim any offsets caused by the input sensor It may be used to null out undesired signal such as a tare weight The Trim Zero TZ command is used to adjust the output to any desired value by loading the appropri
64. y transmitting the response on the daisy chain network The response data will be ripple through any other modules in the chain until it reaches its final destination the Receive input of the host 10to 30Vde GND Figure 3 1 RS 232 Daisy Chain Network The daisy chain network must be carefully implemented to avoid the pitfalls inherent in its structure The daisy chain is a series connected structure and any break in the communications link will bring down the whole system Several rules must be observed to create a working chain 1 All wiring connections must be secure any break in the wiring power ground or communications breaks the chain 2 All modules must be plugged into their own connectors 3 All modules must be setup for the same baud rate 4 All modules must be setup for echo Software Considerations If the host device is a computer it must be able to handle the echoed command messages on its Receive input along with the responses from the module This can be handled by software string functions by observing that a module response always begins with a or character and ends with a carriage return A properly addressed D5000 module in a daisy chain will echo all of the characters in the command including the terminating carriage return Upon receiving the carriage return the module will immediately calculate and transmit the response to the command During this time the module wi

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