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1. Communications distance up to 4 000 feet Digital 8 bit CMOS microcomputer Nonvolatile memory storage for start up values eliminates software initialization Environmental Temperature Range Operating 25 C to 70 C Storage 25 C to 85 C Relative Humidity 0 to 95 noncondensing
2. CMC This output mode produces a data stream each time the input data lines change CMD Disable all Continuous Modes This is the normal condition when the 1700M series are used in a polled system CME Produce an output data stream when the edge trigger input receives a positive transition CMI Enable Continuous Input mode which will allow the module to accept data from a continuous Output module CMT This command enables the Timer Continuous Output Mode In this mode a module will output data periodically at a rate specified by the Continuous Timer CT command All five Continuous Mode commands require no argument and return no data Command 1CMD Response The Continuous Mode selection is saved in non volatile memory and is immediately active when power is applied to the module With the exception of the CMD command all of the Continuous Mode commands are write protected and must be preceded with a WE command Although the Disable command is stored in non volatile memory it is not write protected in order to disable a continuous output module quickly The Continuous Mode setup may be read back with the Read Continuous Mode RCM command Command Set 4 20 Digital Input DI The Digital input command is used to read the logical state of all of the I O lines in parallel The DI command reads the state of both input and output lines Command 1DI Response 1234 The number of data bits read back is a fu
3. Command 1RS Response 31020102 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 SetUp Command 5 6 Command 1WE Response iS Command 1RR Response Up to this 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 Bits 3 and 4 These two bits of byte 2 are not used and should be set to 0 Table 5 2 Byte 2 Linefeed Parity and Baud Rate BYTE 2 FUNCTION DATA BIT 7 65 4 3 2 1 0 LINEFEED 1 NO LINEFEED 0 NO PARITY 0 0 NO PARITY 1 0 EVEN PARITY 0 1 ODD PARITY 1 1 2 STOP BITS MODBUS RTU ONLY 0 1 STOP BIT MODBUS RTU ONLY 1 115200 BAUD 1 0 0 0 57600 BAUD 1 0 0 1 38400 BAUD 0 000 19200 BAUD 0 0 0 1 9600 BAUD 0 0 1 0 4800 BAUD 0 0 1 1 2400 BAUD 0 1 00 1200 BAUD 0 1 0 1 600 BA
4. Command Set 4 29 The RRcommandis required to modify the baud rate of a module see Setup section The RR command will not affect the output data or the Event Counter The RR command is write protected Read Watchdog Timer The Read Watchdog Timer RWT command reads the time interval necessary to activate the watchdog timer The data is scaled in minutes Command 1RWT Response 00010 00 10 minutes Command 1RWT Response 1RWT 00010 0002 10 minutes In each of the two example commands the response data indicates that the watchdog timer period is 10 minutes The watchdog timer value may be set with the Watchdog Timer WT command Setup Command SU Each module contains an EEPROM Electrically Erasable Programmable Read Only Memory which is used to store module setup information such as address baud 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 commandis so importantto 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 inf
5. In continuous mode a D1711M 1712M module produces a response to a 101 command without actually receiving the command The output data string may be triggered in one of three ways Timer Mode In this mode a software timer is activated in the module with the Continuous Timer CT command The CT command specifies a time period that repeats indefinitely After each timeout the module will output the status data The module will periodically output the digital input data until the continuous mode is disabled Edge Trigger Mode In this mode the D1711M 1712M will output a data string when it receives a trigger signal on the BOO EV I O Pin The edge trigger mode will produce an output in response to an external event It also provides a means of daisy chaining several continuous output modules together Change Mode In this mode the D1711M 1712M continuously monitors the status of the I O lines If a change is detected in status an output data message is initiated Continuous Input A module setup for continuous input will respond to data produced by a continuous output module The data string from a continuous output module is interpreted as an output command by a continuous input module This allows data to be read at one module and replicated at the outputs of another module without a host computer Continuos Input Output 6 2 Continuous Input Output Commands The D1711M 1712M modules contain several commands to setup the continuous
6. The two lowest order hex digits of the sum are BO which agrees with the transmitted checksum Note that the transmitted checksum is the character string equivalent to the calculated 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 1700M Command Set Command Definition Typical Typical Command Response Message Message ACK Acknowledge 1ACK i CB Clear Bit 1CBOC Clear Position 1CP12 id DI Digital Input 1DI 8007 DO Digital Output 51001234 Read Assignments 1RA OFOF RAB Read Assignment Bit 1RABO1 O RAP Read Assignment Pos 1RAPO1 Command Set 4 13 RB Read Bit 1RBOF 1 RD Read Data 1RD 99999 99 RE Read Event Counter 1RE 0001234 RID Read Identification 1RID BOILER RIV Read Initial Value 1RIV OFOF RMA Read Modbus Address 1RMA 0105 RP Read Position 1RP15 0 RS Read Setup 1RS 31070102 RSU Read Setup 1RSU 31070102 RWT Read Watchdog Timer 1RWT 00010 00 SB Set Bit 1SBOC t SP Set Position 1SP12 k WE Write Enable 1WE The following 1700M commands are Write Protected AIB Assign Input Bit 1AIBOF P AIO Assign Input Output 1AIOOFOF Assign Input Position 1AIP
7. Command 1CMD Response The CMD is not write protected and a Write Enable WE command is not required To avoid communications collisions the host should wait for a continuous output response and then immediately issue the CMD command In our current example the host has 10 seconds to issue the CMD command so the likelihood of a collision is remote It is possible for the host to disable the continuous mode even if the Continuous Timer is setfor 0 seconds The host mustissue the CMD command immediately afterthe carriage return from the D1712M is received When the D1712M reads a or character on the communications line it will temporarily halt the continuous mode output and look for an address character If the D1712M detects its own address it will read and process the rest of the command Otherwise it will resume the continuous mode output B Timer Mode With Outputs This configuration is shown in Figure 1 However this time the D1712M is setup with digital outputs For example the high order 7 bits could be configured as outputs Command 1AIOFFOO Response Setup the Continuous Mode just like example A Command 1CT 00010 00 Response 1CMT Response x Continuos Input Output 6 5 The D1712M will continuously output the status of the I O lines including the outputs every 10 seconds However with this setup the host may respond with DO SB CB or other output commands to c
8. The input state is read by the microprocessor through an input protection circuit consisting of a 100K resistor and diodes This allows the input values Functional Description 2 3 to range from 0 to 30V without damaging the microprocessor Note that with the output driver off the 100K resistor produces a leakage current if the l O line is greater than 5V When a read function is performed on an I O pin the actual logical state of the pin is read back even if the pin is configured as an output this provides a means to verify the state of the output CONTROL C INPUT AC 184001 2 3 Digital Outputs Used With Relays Figure 2 3 shows typical connections to solid state relays and electrome chanical relays When electromechanical relays are used always include a flyback diode to avoid damage to the output driver Functional Description 2 4 EVENT COUNTER pu OUTPUT DRIVER pe OUTPUT Figure 2 4 D1711M D1712M Events Counter Circuit Figure 2 4 is a detail schematic of the BOO EV pin This pin is identical to all other pins but it has the event counter circuitry added on The event counter circuitry consists of input protection components and a capacitor to provide some noise filtering The event data is buffered by a Schmitt trigger gate which outputs the event signal to the microprocessor The microprocessor contains a user programmable filter to debounce the event counte
9. 30 1E 00011110 158 9E 10011110 31 1F 00011111 159 9F 10011111 32 20 00100000 160 AO 10100000 33 21 00100001 161 At 10100001 ACTIOTMOOVAB 22 00100010 23 00100011 24 00100100 25 00100101 26 00100110 27 00100111 28 00101000 29 00101001 2 00101010 2B 00101011 2C 00101100 2D 00101101 2E 00101110 2F 00101111 30 00110000 31 00110001 32 00110010 33 00110011 34 00110100 35 00110101 36 00110110 37 00110111 38 00111000 39 00111001 3A 00111010 3B 00111011 3C 00111100 3D 00111101 00111110 00111111 40 01000000 41 01000001 42 01000010 43 01000011 44 01000100 45 01000101 46 01000110 47 01000111 48 01001000 49 01001001 4 01001010 4B 01001011 D 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 ASCII Table 2 Hex Binary 10100010 10100011 10100100 10100101 10100110 10100111 10101000 10101001 10101010 10101011 10101100 10101101 10101110 10101111 10110000 10110001 10110010 10110011 10110100 10110101 10110110 10110111 10111000 10111001 10111010 10111011 10111100 10111101 10111110 10111111 11000000 11000001 11000010 11000011 11000100 11000101 11000110 11000111 11001000 11001001 11001010 11001011 7N xz cdomxovozzre c 0o 7 0002753 75
10. The number of words required may be adjusted to a value most appropriate for a specific device The word length can vary from 1 to 8 words specified by bits 0 2 A word length of 0 is not allowed As an example a D1712M has 15 I O lines and a typical setup for this device would be 31070102 The 02 indicates that the device is setup for two words or 16 bits of data A typical DO command to this unit would be Command 1D01234 Response Since the D1712M is setup for two words it will accept the four digits of hex data If the data length is incorrect an error will be generated Command 1DO12345 Response 21 SYNTAX ERROR SetUp Command 5 9 The word length setup also affects the parallel readback commands such as Command 1DI Response ABCD Notice that with a word setup of 2 the DI command returns 2 words of data The same effect occurs with the RA and RIV commands It is possible to setup a module with a word length that does not correspond with the physical I O data width For example the D1712M may be setup with word length 1 Setup data 31070101 With this setup the DI command returns eight bits of data Command 1DI Response CD The correct DO argument is now two hex digits Command 1D034 Response j A word length of 1 may be appropriate for the D1712M if only eight bits of the device are used or if maximum communications speed is desired Regardless of the word
11. This pin is normally left open or pulled up to 5V When grounded the H1750 will be in Continuous Mode When using H1750M or H1770M Digital I O boards in a multiple continuous application the Default line from the preceding board or module must be connected to the Cont terminal Pin6 GND This is the power supply ground connection Itis also the signal ground for the serial port Output Connections The digital I O connections are made through the connector The output connections are made to be compatable with industry standard 16 or 24 channel solid state relay racks The 50 pin ribbon connector near the edge of the board is wired as follows Pin Signal 1 B17 3 B16 5 B15 7 B14 9 B13 11 B12 13 B11 15 B10 17 BOF 19 BOE 21 BOD 23 BOC 25 BOB 27 BOA 29 B09 31 B08 33 B07 35 B06 37 B05 39 B04 41 B03 43 B02 45 B01 47 Boo All even pins are connected to GND All other pins are no connection Appendix D 1700M Series Specifications 1700M Series Specifications typical 25 C and nominal power supply unless otherwise noted H1750M H1770M Digital Input Output Boards H1750M 24 digital input output bits with RS 232 or RS 485 output H1770M 64 digital input output bits with RS 232 or RS 485 output User can define any bit as an input or an output Inputs Outputs can be read set individually or in parallel Input voltage levels 0 10V without damage Input switching levels High 3 5V min Low 1 0V max Output
12. c3o o 0o00o0om9m Hex Binary 4C 01001100 4D 01001101 4E 01001110 4F 01001111 50 01010000 51 01010001 52 01010010 53 01010011 54 01010100 55 01010101 56 01010110 57 01010111 58 01011000 59 01011001 5A 01011010 5B 01011011 5G 01011100 5D 01011101 5E 01011110 5F 01011111 60 01100000 61 01100001 62 01100010 63 01100011 64 01100100 65 01100101 66 01100110 67 01100111 68 01101000 69 01101001 6A 01101010 6B 01101011 66 01101100 6D 01101101 6E 01101110 6F 01101111 70 01110000 71 01110001 72 01110010 73 01110011 74 01110100 75 01110101 D 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 ASCII Table A 3 Hex Binary 11001100 11001101 11001110 11001111 11010000 11010001 11010010 11010011 11010100 11010101 11010110 11010111 11011000 11011001 11011010 11011011 11011100 11011101 11011110 11011111 11100000 11100001 11100010 11100011 11100100 11100101 11100110 11100111 11101000 11101001 11101010 11101011 11101100 11101101 11101110 11101111 11110000 11110001 11110010 11110011 11110100 11110101 cce M See Sse 2 U 118 119 120 121 122 123 124 125 126 127 Hex Binary 01110110 01110111 01111000 01111001 01111010 01111011 01111100 01111101 01111110 01111111 D 246 247 248 249 250 251 252 253 254 2
13. numbers are hexadecimal between the values of 0000 and ffff They represent a percentage of the full scale value If your getting readings back that move as your input moves then the Modbus protocol is working successfully For more information how to compute these values consult the DGH Users Manual for your product 0 99 N Getting Started 1 8 Modbus Installation Verification 1 The 1700M product is now configured for the proper Baud Rate and Modbus Slave Address The module can now be connected directly to the Modbus Master Or it can be functionally checked To functionally verify the operation of the Modbus protocol make sure that the Default terminal is no longer connected to the GND terminal From the Utility Software main menu select Tools and then select Evaluation Screens and then Modbus I O Screen Click on the Settings button and change the Baud Rate to the value that the module is configured for Press the Advanced button Select 8 Data bits RTS Only No Parity and 2 Stop Bits Press the Update or Open button Select the Modbus Slave Address to the same value as the module is configured for Select Modbus function 04 and register O00 Press the Transmit button Hexadecimal numbers will appear in the Response box These numbers are hexadecimal between the values of 0000 and ffff The
14. 1 Use the setup SU command to set the desired communications parameters In this case the D1712M will be setup for address 2 Command 1SU32070102 Response 2 The BOO I O line must be assigned as an inputto acceptthe trigger signal Other l O lines may be assigned as inputs or outputs depending on the application Command 2AIOFFOO Response y This command assigns BOO through BO7 as inputs and B08 through BOE as outputs 3 The Continuous Timer CT command may be used to specify a delay time between the Trigger signal and the output data string This feature is useful in some applications when multiple modules are tied together which will be illustrated in other examples For this and most edge trigger applications set the Continuous timer to 0 seconds Continuos Input Output 6 7 Command 2CT 00000 00 Response 4 Enable the edge trigger mode with the Continuous Mode Edge trigger CME command 5 When the D1712M senses a positive going trigger on the BOO EV line it will perform the equivalent of a 201 command and output the data Response 2DI1235B3 6 The host may terminate the edge trigger mode with a Continuous Mode Disable CMD command Precautions must be used to avoid communica tions collisions between the host command and responses from the module The best method of disabling the continuous mode is to issue the long form version of the CMD command Command 2CMD Response 2CMD30 The
15. 19 BOE 21 BOD 23 BOC 25 BOB 27 BOA 29 B09 31 B08 33 B07 35 B06 37 B05 39 B04 41 B03 43 B02 45 B01 47 Boo H1770M B 3 All even pins are connected to GND All other pins are no connection J3 Pin Signal 17 B1F 19 B1E 21 B1D 23 B1C 25 B1B 27 BiA 29 B19 31 B18 33 B17 35 B16 37 B15 39 B14 41 B13 43 B12 45 B11 47 B10 All even pins are connected to GND All other pins are no connection J4 Pin Signal 17 B2F 19 B2E 21 B2D 23 B2C 25 B2B 27 B2A 29 B29 31 B28 33 B27 35 B26 37 B25 39 B24 41 B23 43 B22 45 B21 47 B20 H1770M B 4 Even pins 18 50 are connected to GND All other pins are no connection J5 Pin Signal 17 B3F 19 B3E 21 B3D 23 B3C 25 B3B 27 B3A 29 B39 31 B38 33 B37 35 B36 37 B35 39 B34 41 B33 43 B32 45 B31 47 B30 Even pins 18 50 are connected to GND All other pins are no connection Appendix C H1750M 24 Channel Digital I O Board The H1750M is designed to interface to an Opto 22 16 or 24 channel solid state relay backplane or equivalent backplanes with the standard pin out Hook Up Plug the H1750M into the backplane header Be sure the board is centered over the header and latch the board to the header The H1750M contains line drivers for both RS 232 and RS 485 Select the desired communications link with the three shorting bars near the edge of the H1750 Move the three shunts to the RS 232 position to select RS 232 Move the three shunts to the RS 485
16. 232C no special machine language software drivers are necessary for operation The mod ules 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 32 RS 485 modules may be strung together on one cable 124 with repeaters A practical limitfor RS 232C units is about ten although a string of 124 units is possible The modules communicate with the host on a polling system that is each 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 communications collisions and data errors Communication to the 1700M series is performed with two or three character ASCII command codes such as DO for Digital Output A complete description of all commands is given in the Chapter 4 A typical command response sequence would look like this Command 1RD Response 99999 99 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 norm
17. The Continuous Input Addresses CIA may be set to any value independent of the polled address Chapter 7 Power Supply D1711M D1712M modules may be powered with an unregulated 10 to 30Vdc Power supply ripple must be limited to 5V peak to peak and the instantaneous ripple voltage must be maintained between the 10 and 30 volt limits at all times 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 The D1711M D1712M 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 voltage The D1711M D1712M 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 watts The power supply must be able to provide 3 24 0 125 amps In some cases a small number of modules may be operated by stealing power from a host computer or terminal Many computers provide a 15 volt output on the RS 232C DB 25 connector 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 commun
18. assistance Symptom D1711M D1712M events counter not counting properly 1 Check that the frequency of the signal being counted is less than 60Hz 2 Ensure that the signal levels are swinging below 1 0Vdc and greater than 3 5Vdc Appendix A ASCII Table Table of ASCII characters A and their equivalent values in Decimal D Hexadecimal Hex andBinary 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 C 3 03 00000011 131 83 10000011 D 4 04 00000100 132 84 10000100 NE 5 05 00000101 133 85 10000101 F 6 06 00000110 134 86 10000110 7 07 00000111 135 87 10000111 H 8 08 00001000 136 88 10001000 9 09 00001001 137 89 10001001 J 10 0A 00001010 138 8A 10001010 K 11 0B 00001011 139 8B 10001011 L 12 0C 00001100 140 8C 10001100 M 13 OD 00001101 141 8D 10001101 N 14 OE 00001110 142 8E 10001110 O 15 OF 00001111 143 8F 10001111 P 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 T 20 14 00010100 148 94 10010100 U 21 15 00010101 149 95 10010101 22 16 00010110 150 96 10010110 N 23 17 00010111 151 97 10010111 X 24 18 00011000 152 98 10011000 Y 25 19 00011001 153 99 10011001 2 26 1A 00011010 154 9A 10011010 q 27 1B 00011011 155 9B 10011011 28 1C 00011100 156 9C 10011100 29 1D 00011101 157 9D 10011101
19. 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 4 which generates long responses the long response format will be covered a little later The prompt character must be followed by a single address character identifying the module to which the command is directed Each module attached to a common communications port must be setup with its own unique address so that commands may be directed to the proper unit Module addresses are assigned by the user with the SetUp SU command For ease in debugging printable ASCII characters such as 1 ASCII 31 or A ASCII 41 are the best choices for address characters The address character is followed by a two or three character command which 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 full later in this section Com mands must be transmitted as upper case characters Atwo character checksum may be appended to any command message as a user option See Checksum section below 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 Data Str
20. 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 re transmitting 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 300 33 30ms 600 16 70ms 1200 8 33ms 2400 4 17ms 4800 2 08ms 9600 1 04ms 19200 520us 38400 260us 56700 130us 115200 65us One delay time is accumulated for each module in the chain For example iffour 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 error 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 commu nications delay is seldom necessary in an RS 232C daisy chain since each module in the chain adds one char
21. in Modbus mode can be returned to ASCII protocol mode by connecting a jumper wire betweenpins GND and Default pin This places the module in Default Mode where the module will only communicate at 300 baud no parity DGH ASCII protocol and answer to any address While in Default mode transmit an MBD com mand to internally disable the Modbus protocol Following the MBD command a device reset must occur The reset is necessary to activate the 1700M ASCII protocol A reset can occur by removing the Default jumper performing a power up reset or by trans mitting a Write Enable WE and Remote Reset RR command se quence After a reset is performed the module is in 1700M ASCII protocol mode Command 1MBD Response Command 1MBD Response 1MBD2E Read Assignment RA The Read Assignment command is used to read back the data direction configuration of all the I O lines The assignments are represented in hexadecimal notation with a 1 signifying an output assignment and a 0 indicating an input assignment The length of the hex data string will vary according to the number of I O lines available and the number of words setup in the device see Setup section The LSB is always to the right Command 1RA Response 00FF This response indicates that the most significant eight I O lines are config ured as inputs and the least significant eight lines are configured as outputs For adevice thatis setup with a word l
22. may be used as addresses Table 5 1 Byte 1 ASCII Printable Characters HEX ASCII ASCII ASCII ASCII 21 51 Q 68 h 2 3B 52 R 69 i 25 3C lt 53 5 6A j 6 amp 3D 54 6B k 07 gt 55 uU 6C 1 28 56 V 6D m 29 40 e 5 6E n 2 41 58 X 6F 2B 42 B 59 Y 70 p DG 43 Cc 2 71 q 2D 44 D 5B 72 2 45 E 5C 73 s 2F 46 50 7A t 30 0 47 G BE A 75 u 31 1 48 H 5F 76 v 32 2 49 60 77 w 33 3 J 61 a 78 34 4 4B K 62 b 70 35 5 4C L 63 c 2 36 6 4D M 64 d 7B 37 7 4E N 65 7C 38 8 4F 66 f 7D 39 9 50 67 g SetUp Command 5 4 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 modules are terminated with a carriage return ASCII 0D Most terminals will generate a automatic linefeed when a Carriage return is detected However for terminals that do not have this capability the modules 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 transmitted When using the command prompt the linefeed characters are inclu
23. of the digital inputs on module 1 is recreated at the digital outputs of module 2 Since module 1 is continually outputting data on the communications lines any changes inthe state ofthe digital inputs on module 1 will be transmitted to module 2 and the output lines will change to reflect the new state To setup module 2 for Continuous Input Mode 1 Setup the module for an address different from the Continuous Output module In this example the Continuous Output module is setup for address 1 The Continuous Input module will be setup for address 2 Command 1SU32070102 Response Any address may be used for the Continuous Input module as long as it is different from module 1 Continuos Input Output 6 14 The communications setups for both modules must match They must be setup with identical baud rate and parity settings Also the word length setup must be identical 2 Assign the digital I O lines to be outputs Command 2AIOFFFF Response d 3 The Continuous Input module must be assigned a Continuous Input Address CIA This address is different from the normal communications address This address is necessary so that the continuous input module may selectively read data on the communications bus The full purpose of the CIA will be demonstrated in the next few examples In this case module 2 is setup to respond to data from module 1 Character 1 or ASCII 31 is the Continuous Input Addres
24. of the specified I O line in positive logic Command 1RIP15 Response 1 Command Set 4 28 Note that in the two command examples the same I O line is addressed The RIB and RIP will read the state of any line whether it is configured as an input or an output Therefore it is useful in monitoring the true state of output data lines Read Setup The Read SetUp RSU command reads back the setup information loaded into the module s nonvolatile memory with the SetUp SU command The response to the RSU command is four bytes of information formatted as eight hex characters 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 Command 1RSU Response 31070102 Command 1RSU Response 1RSU31070102E3 The Read Setup RS command performs the same function and is included to be compatible with the D1000 2000 series Command 1RS Response 31070102 Command 1RS Response 1RS310701028E Remote Reset The Remote Reset RR command allows the host to perform a program reset on the module s microcomputer This may be necessary if the module s internal program is disrupted by static or other electrical distur bances Command 1RR Response 1RR Response 1RRFF
25. recommends that you insure the product for value prior to shipping Items should not be returned collect as they will not be accepted Shipping Address DGH Corporation Hillhaven Industrial Park 146 Londonderry Turnpike Hooksett NH 03106 Chapter 1 Getting Started Introduction The 1700M series of digital I O to computer interfaces provide computer monitoring and control of devices through solid state relays or TTL signals The status of inputs and outputs is communicated to the hostin Modbus or DGH ASCII format using RS 232C or RS 485 serial communications With the 1700M series the user can control digital inputs and outputs individually or all at once Any channel may be designated as an input or output by the user Many industrial applications require a safe start up condition to prevent accidents at critical points in the process The onboard nonvolatile EEPROM memory stores the user specified initial condition input or output of each channel thereby eliminating the need for software initialization routines when power is applied or restored The 1700M series may be setup in special modes which allow them to communicate without being polled by a host computer Collectively these modes are called Continuous Input Output Modes The Continuous Input Output Modes are only available when using DGH ASCII communications In many applications the burden on the host may be greatly simplified and in some cases the host may be elim
26. setup the rightmost hex digit of the bit datais always the least significant I O data The most significant data is appended or truncated as necessary corresponding to the word length setup It is also possible for the word length to be greater than the physical data width of the device The D1712M may be setup with a word length of 3 31070103 In this case all parallel data values must be 24 bits or six hex digits wide Command 1D0123456 Response 5 Command 1DI Response 003456 The D1712M contains 15 l O lines For the DO command the most significant nine of the 24 bits will be ignored The DI command will return with 1 data for the nine most significant bits SetUp Command 5 10 The deliberate use of dummy data may seem wasteful but it can be useful for streamlining host software For example in a system with a mix of 24 and 15 bit devices the host software may be simplified by standardizing to word length 3 for all devices The word length setup has no affect on commands using single bit Bit or Position addressing BYTE 4 FUNCTION DATA BIT 7 6 5 4 3 2 1 0 NOT USED X X NO FILTER 0 0 5ms 0 1 20ms 1 0 50ms 1 1 1 WORD 0 0 0 1 2 WORDS 0 0 1 0 3 WORDS 0 0 1 1 4 WORDS 0 1 0 0 5 WORDS 0 1 0 1 6 WORDS 0 1 1 0 7 WORDS 0 1 1 1 8 WORDS 1000 Setup Hints Until you become completely familiar with the SetUp command the best method of changing setups is to change one parameter at atime and to
27. the Events Counter and automatically clears the count to zero Command 1EC Response 0000123 The EC command eliminates a problem that may occur with a Read Events RE and Clear Events CE command sequence Any counts that may occur between the RE CE sequence will be lost The EC command guarantees that the Event Counteris read and cleared without missing any counts Identification ID The IDentification ID command allows the user to write a message into the nonvolatile memory which may be read back at a later time with the Read IDentification RID command It serves only as a convenience to the user and has no other affect on module operation Any message up to 16 characters long may be stored in memory Useful information such as the module location calibration data or model number may be stored for later retrieval Message examples Command 1IDBOILER ROOM module location Response Command 1IDBOILER ROOM module location Response 1IDBOILER ROOMO2 Command 11D 12 3 88 calibration date Response 5110 3125 model number Response Pa The ID command is write protected Command Set 4 22 Since the ID command has a variable length syntax command checksums cannot be appended to the message Initial Value IV The Initial Value command allows the user to preset the startup condition of the digital outputs When the 1700M unit is powered up it reads data from the non volatile memory t
28. 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 as 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 D1711M unit and you wish to set the unit to echo so that it may be used a daisy chain See Communications Read out the current setup with the Read Setup command Command 1RS Response 81070102 SetUp Command 5 11 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 Command 1SU31070502 Response Verify that the module is echoing characters and the setup is correct By using the RS command and changing one setup parameter ata 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
29. 000 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 If the 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 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 Ifthe 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 Symptom RS 485 Module is not responding to commands 1 Perform steps 1 2 4 5 and 6 listed above Troubleshooting 8 2 2 Ensure that module RS 485 Data line module terminal pin 7 is connected to the Host RS 485 Data 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
30. 15 Assign Output 1AOBOF T AOP Assign Output Pos 1AOP15 T CE Clear Event Counter 1CE Event Read amp Clear 1EC 0001234 ID Identification 1IDBOILER IV Initial Value 1IVOFOF E MBD Modbus Disable 1MBD MBR RTU Enable Modbus 1MBRO1 T RR Remote Reset 1RR i SU Setup 1SU31070102 WT Watchdog Timer 1WT 00010 00 The following 1700M commands used with the special Continuous Input Output Modes CIA Continuous Input Address 1CIA31 CMC Continuous Mode Change 1CMC CMD Continuous Mode Disable 1CMD Continuous Mode Edge 1CME CMI Continuous Mode Input 1CMI Continuous 1CMT 3 CT Continuous Timer 1CT 00010 00 RCM Read Continuous Mode 1RCM D RCT Read Continuous Timer 1RCT 00010 00 RIA Read Input Address 1RIA 31 1700M Command Set ACKnowledge ACK The ACKnowledge commandis a hand shaking command that may be used with any command that will affect the the digital outputs such as the Digital Command Set 4 14 Output DO command It is used to confirm the data sent to a module and adds another level of data security to guard against transmission errors when performing output functions Command 1ACK Response Command HACK Response 1ACK2A The ACK command is used in conjunction with the form of an output command For example Command 1DOFFFF Response 1DOFFFF06 Note that the command is echoed ba
31. 1700M USERS MANUAL REVISED 2 1 07 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 isbelieved to be accurate however no responsibility is assumed for possible inaccuracies or omissions Applications information in this manual is intended as suggestions for possible use of the products and not as explicit performance in a specific application Specifica tions may be subject to change without notice The 1700M series are not intrinsically safe devices and should not be used in an explosive environment unless enclosed in approved explosion proof housings CHAPTER 1 CHAPTER 2 CHAPTER 3 CHAPTER 4 CHAPTER 5 CHAPTER 6 CHAPTER 7 CHAPTER 8 Appendix A Appendix B Appendix C Appendix D TABLE OF CONTENTS Getting Started Default Mode Quick Hook Up Functional Description Block Diagram Communications Data Format RS 232 Multi party Connection Software Considerations Changing Baud Rate RS 485 RS 485 Multidrop System Command Set Modbus Functions Table of Commands User Commands Error Messages Setup Information and Command Command Syntax Setup Hints Continuous Input Output Applications Power Supply Troubleshooting ASCII Table H1770M 64 Channel I O Board H1750M 24 Channel Digital I O 1700M Series Specifications 3 2 3 3 3 4 3 5
32. 3 6 3 7 4 3 4 12 4 13 4 31 WARRANTY DGH warrants each 01700 series module to be free from defects in materials and workmanship under normal conditions of use and service and will replace any component found to be defective on its return to DGH transportation charges prepaid within one year of its original purchase DGH assumes no liability expressed or implied beyond its obligation to replace any component involved Such warranty is in lieu of all other warranties expressed or implied WARNING The circuits and software contained in D1700 series modules are proprietary Purchase of these products does not transfer any rights or grant any license to the circuits or software used in these products Disassembling or decompiling of the soft ware program is explicitly prohibited Reproduction of the software program by any means is illegal As explained in the setup section all setups are performed entirely from the outside of the 01700 module There is no need to open the module because there are no user serviceable parts inside Removing the cover or tampering with modify ing or repairing by unauthorized personnel will automatically void the warranty DGH is not responsible for any consequen tial damages RETURNS When returning products for any reason contact the factory and request a Return Authorization Number and shipping instructions Write the Return Authorization Number on the outside of the shipping box DGH strongly
33. 55 ASCII Table A 4 Hex Binary 11110110 11110111 11111000 11111001 11111010 11111011 11111100 11111101 11111110 11111111 Appendix B H1770M 64 Channel Digital I O Board The H1770M Digital I O interface is designed to provide remote I O capability for computers modems and other devices with standard serial ports Commands communicated over standard RS 232 or RS 485 links may be used to control or read up to 64 digital I O channels The H1 700M is designed to interface to industry standard solid state relay racks Up to four 16 channel racks may be connected to the H1770M with ribbon cable connectors The 64 I O channels may be configured to be inputs or outputs in any combination designated by the user The input output configuration may be changed at any time through the communications port The I O assign ments are saved in nonvolatile memory and are automaticly loaded when the unit is powered up Getting Started RS 232 RS 485 Selection The H1770M contains drivers to connect to either RS 232 or RS 485 ports The H1770M must be configured to the desired interface before it is connected to the host The H1770 has a 12 pin header near the edge of the board marked RS 232 RS 485 To configure the board for RS 232 make sure the three jumpers are installed adjacent to the RS 232 label To configure the board for RS 485 make sure the jumpers are adjacent to the RS 485 label Pin Connections The host interface connection i
34. 70102 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 1 which in this particular case remains unchanged To change the module 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 1SU32070102 When this command is sent the module address is changed from 1 to 2 The module will no longer respond to address 1 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 SetUp Command 5 3 The most significant bit of byte 1 bit 7 must be set to 0 In addition there are four ASCII codes that are illegal for use as an address These codes are 00 00 24 23 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 124 possible addresses that can be loaded with the SU command It is highly recom mended that only ASCII codes for printable characters be used 21 to 7E which greatly simplifies system debugging with a dumb terminal Refer to Appendix A for alist of ASCII codes Table 5 1 lists the printable ASCII codes that
35. AE Figure 1 2 RS 485 Quick Hook Up 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 1kQ resistor in series with the RS 232 output Gettina Started 1 5 10 to 30 Yde Power Supply D1712 DIGITAL IO rV B 10 FEES REE Eu 66 Note If using aDB 25 connector ground is tied to pin Pin 3 iz tied to TRANSMIT and pin 2 is tied to RECEIVE on the module Figure 1 3 RS 485 Quick Hook Up with an RS 232 Port Software Quick Start The 1700M series modules are initialized at the factory to communicate using the 1700M ASCII protocol This allows for all setup and configurations to be easily performed using the setup software After the setup process has been completed the 1700M can be placed in Modbus RTU pro
36. Continuous Output mode Modules 2 3 amp 4 are setup for Continuous Input The three Continuous Input modules are all setup with a Continuous Input Address CIA of ASCII 31 or character 1 This means that each of these three modules will accept the data from module 1 as an output command The outputs of modules 2 3 and 4 will replicate the input data of module 1 Continuous Input Protocol Notes A module in continuous input mode will respond to data in the form of 1DI80F096 This is typical of a data string that may be produced by a continuous output module The 1 denotes the address of the module producing the data stream The Continuous Input Module will respond to this data only if it is programmed to read data from module 1 The Continuous Input Address CIA is used to specify which data strings will be examined by the Continuous Input module The CIA command is used to specify the ASCII code for the address character In this case to allow the module to respond to data with the address tag 1 use the command Command 2CIA31 Response The number 31 is the ASCII code for character 1 An important consideration in constructing a continuous input output sys tem is to make sure that all modules tied to the communications bus have unique address as specified by the SU command This allows an intelligent host to use the modules in a normal polled manner This greatly simplifies setup and debugging
37. D Continuous Output Disabled E Continuous Output Edge Trigger l Continuous Input T Continuous Output Timer Read Continuous Timer RCT The RCT command is used to read back the time value set by the Continuous Timer CT command Command 1RCT Response 00005 00 The Continuous Timer data is scaled in units of seconds The Continuous Timer function is detailed in Chapter 6 Read Input Address RIA The RIA command reads back the Continuous Input Address stored in non volatile memory This command in useful only for modules that are to be used in Continuous Input Mode Chapter 6 Command 1RIA Response 41 The response to the RIA command is the ASCII code of the Continuous Input Address character In this example 41 is the ASCII code for character A Read Data RD The Read Data RD command is used to read analog data from the devices Since the Digital I O products do not acquire analog data this command will always result in a fixed response Command 1RD Response 99999 99 Command 1RD Response 1RD 99999 99D9 The RD commandis included in the 1700 series to be compatible with other our products In many systems that include analog input modules the host will acquire data with a software loop containing the RD command The RD Command Set 4 26 command is included in digital I O products so they may be included in the scanning loop A proper response from an RD command is a good indicatio
38. UD 0 1 1 0 300 BAUD 0 1 1 1 SetUp Command 5 7 Byte 3 This byte contains the setup information for additional communications options The default value for this byte is 01 Echo When bit 2 is set to 1 the module will retransmit any characters it has received on the communications line This option is necessary to daisy chain multiple 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 O 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 O and 1 is equal to the amount of time required 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 O 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 modules will respond immediately after a command terminated by a CR and will ignore the linefeed To avo
39. acter 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 Communications 3 6 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 resetin 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 Terminal 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 sat
40. al response indicated by a prompt 2 an error message indicated by a prompt 3 a communications time out error Communications 3 2 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 assumed that no response data is forthcoming This error usually results when an improper command prompt or address is transmitted The table below lists the timeout specification for each command Mnemonic Timeout ACK CB CE CP DI DO RA RAB RAP RB lt 5 0 ms RD RP RS RSU SB SP RIA ROM RR WE EC RE RWT RID RIV RCT AIB AIP AOB lt 15 0 ms AOP CIA CMC CMD CME CMT WT CT SU AIO ID IV lt 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 format 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 be
41. 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 or powering down This extra level of write protection is necessary to ensure that communications 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 31070102 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 81070102 Let s say we wish to change the baud rate to 9600 baud The code for 9600 baud is 010 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 Command 1SU31020180 Response x This sequence 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 sequence We can use the Read Setup RS command to check the setup data
42. bi directional RS 485 system there are unavoidable periods of time when all stations on the line are in receive mode During this time the communications lines are left floating and are very susceptible to noise To prevent the generation of random characters the lines should be biased in a MARK condition as shown in Figure 3 2 The 1K resistors are used to keep the DATA line more positive than the DATA line when none of the RS Communications 3 8 485 transmitters are on When enabled the low impedance of an RS 485 driver easily overcomes the load presented by the resistors 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
43. ck with a checksum 06 which is the case any time the prompt is used However in the case of the DO command the output data has not been changed at this point The command data is echoed back so that the host may verify that the correct message has been received by the module If the command data is confirmed to be correct the host may then activate the command by issuing an ACK command Command 1ACK Response Only at this point will the outputs be affected by the DO command If the host detects an error in the response data it may recover by simply repeating the original command For example Command 1DOFFFF Response 1 DOFFFE05 In ths case the response data does not match the original command indicating that the module may have received the command incorrectly due to noise on the transmission line However the erroneous data does not reach the output since the module must receive an ACK to complete the command To correct the error the host may re issue the original command Command 1DOFFFF Response 1DOFFFF06 This time the response data is correct and the DO command may be Command Set 4 15 completed by sending the acknowledgement Command 1ACK Response 3 Commands that require ACK handshaking are AIB AIO AIP AOB AOP CB CP DO SB and SP An ACK command used without an associated output command will generate a COMMAND ERROR Assign Input Bit AIB Assign Input Position AIP Assign O
44. command is issued by the host and then the host looks for the correct response string to be returned by the D1712M If the correct response string is detected then the host knows that the continuous mode has been disabled If the correct response string is not received it may be assumed that the CMD command collided with response data from the module The host simply repeats the CMD command until the correct response is obtained Communications collisions are not harmful to RS485 hardware However the host serial input must be able to accept framing errors and noise characters gracefully when collisions occur Continuos Input Output 6 8 D Continuous Output Daisy Chain With Host Figure 4 ADDRESS 3 ADDRESS 2 ADDRESS 41 EDGE MODE EDGE MODE TIMER MODE This configuration uses one module address 1 in Timer mode which produces a trigger signal on the Default line to trigger another module address 2 which is set for Edge trigger mode The third module address 3 is set up for edge trigger mode and receives its trigger signal from the Default pin of module 2 Additional edge triggered modules may be implemented by connecting the trigger output Default of a module 3 to the trigger input BOO EV of the next module in the series and this connection may be repeated for any additional modules A typical applica tion will have 1 timer module with any number up to 123 of edge triggered modules The net result of this connect
45. d alarm type of inputs where the change of an input indicates an extraordinary event This cuts down the likelihood that two events would occur at the same time 2 Checksums and parity must be used to detect communications errors caused by data collisions Continuos Input Output 6 12 3 The host input port should be setup so that any activity on the input lines is evidence that a change in input status has occurred This will cover the unlikely possibility that two modules are responding at exactly the same time In this case the host may disable the Continuous Mode and poll the modules directly to read the input lines 4 Use the highest baud rate possible to reduce the likelihood of collisions 5 The Continuous Timer may be used to limit responses from a module This particularly useful if an input is likely to turn on and off quickly and constantly causing a continuous stream of data from one module The CT command may be used to set a dead time after a module has produced an output response Command 1CT 00005 00 Response With the Continuous Timer set to 5 seconds module 1 will pause for 5 seconds after each response before resuming scanning the digital I O lines This prevents the module from hogging the communications bus in re sponse to continuously changing input lines G Continuous Input Mode The D1711 M1712M modules may be set to a special mode called Continuous Input Mode which allows the module to respond
46. d by the letter B For example Command 1SBOF This is an example of the Set Bit SB command The command action is directed to the address OF hexadecimal The Position format uses a decimal address preceded by the letter P For example Command 1SP15 This is an example of the Set Position SP command The command action is directed to the I O line address 15 decimal Note that the last two command examples produce the same results The choice of the Bit notation or Position notation is strictly a matter of user preference Logic Convention Most devices in the 1700M family feature open collector transistor outputs to interface directly with solid state relays The control input of the relay is Command Set 4 9 generally connected between the output line and a source of power With conventional relays the output transistor is turned onto sink currentthrough the relay turning the relay on The logic convention used in the 1700M series requires a logical 1 to turn on the relay This means that the output voltage measured at the I O line will be near ground potential low This is an example of negative logic The logic convention used to read input data is positive logic This means that a high voltage potential at the I O line will be read back as a logical 1 A low potential will be read back as a logical 0 Write Protection Many of the commands listed in Table 4 1 are under the heading
47. d to a module as eight 8 bit binary charac ters Command Set 4 2 The actual format of the data is dependent on the type of command desired The example above is the Modbus Read Input Registers function The 01 is the address of the slave device 1700M series being com manded Each slave device must have its own unique address The 04 specifies the Modbus Read Input Registers function This is equivalent to the Read Data command to obtain analog input data The next two characters 00 00 specify the starting address of the registers to be read The first Modicon input register 30001 is addressed as 00 00 Register 30004 is addressed as 00 03 etc The next two characters of this command specify the number of registers to be read including the starting register In this case the two binary characters 00 01 indicates only one register is to be read The final two characters of the command string make up the Cyclical Redundancy Check CRC used to check for errors in the message There are no prompt or terminating characters in the messages All messages must be transmitted as continuous strings Messages are termi nated by a silent interval of at least 3 5 character times A silent interval of more than 1 5 character times marks the beginning of the next message Therefore it is mandatory that the RS 485 bus must be biased in the MARK condition during the silent int
48. ded 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 0 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 0 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 Stop Bits Modbus RTU Only Bit 4 determines the number of stop bits in each communications byte word when no parity is specified The Modbus RTU protocol specifies that each data byte must have two stop bits when no parity is specified In order to provide flexibility and perform in more applications the 1700M can be configured for either one or two stop bits when no parity is specified Bit 4 0 two stop bits 1 one stop bit SetUp Command 5 5 Baud Rate Bits 0 3 specify the communications baud rate The baud rate can be selected from eight values between 300 and 115200
49. e is put in a 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 command to determine all of the setups stored in the module In Default Mode all commands are available A module in Default Mode will respond to any address except the four identified illegal values NULL CR 4 A dummy address must be included in every command for proper responses The ASCII value of the module address may be read back with the RS command An easy way to determine the address character is to deliberately generate an error message The error message outputs the module s address directly after the prompt 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 single 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 am
50. ected 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 by 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 Communications 3 4 4 To Y3 10to 3 Ydc aD Host Receive Pot Figure 3 1 RS 232 Daisy Chain 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 wil
51. empt to load an address greater than 7F will also produce an error An attempt to use the Continuous Input Address CIA command to specify an illegal address or an address identical to the polling address will create 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 Set 4 32 COMMAND ERROR This error occurs when a 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 OUTPUT ERROR An attempt to use a CB SB or SP command to set or clear a digital l O line that has been assigned as an input will generate an OUTPUT ERROR The Digital Output DO command will not generate an OUTPUT ERROR PARITY ERROR A parity error can only occur if the module is setup with parity on see Setup 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 ma
52. ength of 8 the RA command will read back the data direction of 64 I O lines Command 1RA Response 00FFOOFF88110044 Command Set 4 24 Read Assignment Bit RAB Read Assignment Position RAP The RAB and RAP commands are used to read back the input or output assignment of a single I O line These commands use Bit or Position bit addressing to identify the desired bit The 1700M will return an I character if the bit is assigned to be an input or an O character if the bit is assigned as an output Command 1RABOE Response O Command 1RAP15 Response Read Bit Read Position RP The Read Bit command is used to read the logical state of any individual 1 O line input or output The desired bit is specified with the Bit notation Command 1RBOF Response 1 The response data is 1 or 0 character indicating the state of the I O line in positive logic Attempting to read a non existing I O line will result in a VALUE ERROR The Read Position command performs the same function except the data bit is addressed in Position decimal notation Command 1RP15 Response 1 Note that the last two command examples perform the same function Read Continuous Mode RCM The RCM command is used to read back the Continuous Input Output Mode Command 1RCM Response D Command Set 4 25 The response is a single character indicating the Continuous Mode C Continuous Output Change Mode
53. er supplies to power up to 32 modules To expand an RS 485 system even further repeater boxes are available from us to string up to 124 modules on one communications port RS 485 Multidrop System Figure 3 2 illustrates the wiring required for multiple module RS 485 system 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 labelled with notations B R G 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 For wire runs greater than 500 feet total each end of the line should be terminated with a 2200 resistor connected between DATA DATA When using a
54. erly connect the 1700M to a computer serial port using the Quick Hook Up diagrams in Chapter 1 of this manual using either an RS 232 or RS 485 Serial port An optional CA 3 serial cable and wiring diagram may be used to connect an RS 232 module to a DB 9 serial port At the Utility Software main menu select Setup and then select Modules A new dialog screen will open Using the drop down list box screen object select the proper serial port that the module is connected to Press the Settings button to display the serial port settings Select the proper COM port set the baud rate for 300 Press the Advanced button and ensure that the Parity Type is set to Mark Data bits is Seven Flow Control is RTS Only and the Stop Bits are One Press the Open or Update button Select the proper device Model Number from the drop down list box screen object Use only the four digits For example aD1712M should be a 1712 Specify the device address If the Default terminal on the module is connected to the GND terminal then any device address is acceptable If the Default terminal is not connected to the GND terminal then you Press the Read Setup button at the bottom of the dialog screen If no errors were detected then a new dialog screen will appear with all the current module setup values To configure the device for a Modbus system the only
55. erval This is usually accomplished by pull up and pull down resistors on the communications line A typical response to this example command could be 01 04 02 80 00 D8 FO The 01 and 04 characters echo the slave address and the command function For this particular command function the 02 character indicates the number of data characters to follow in this case 2 characters The two character string 80 00 is the value read from Modicon input register 30001 Register data is read back as 16 bits The remaining two characters D8 FO is the CRC for the response The A1000 series of RS 232 to RS 485 protocol converters and repeaters will not operate with the 9 bit data characters used by the Modbus protocol Command Set 4 3 Modbus Functions 01 Read Coil Status This function will read the coil status or digital input status from a 1700M module or board The coil status is returned regardless of whether a bit is configured as digital input or digital output The number of physical coils to turn On or Off is determined by the 1700M and the Setup message SU Each 1700M contains a certain number of physical I O bits At the factory the 1700M is configured such that all the physical I O bits are available for use The Setup Message contains a user selectable variable called Word Length that determines how many bytes of physical I O bits are available Word Length values from 1 to 8 are pos
56. exception responses The end of the chapter explains the ASCII protocol usable 1700M ASCII commands and error messages The user should become familiar with both of these potocols Modbus Protocol Overviw This document describes the Modbus RTU protocol option included in the 1700M series This implementation of the Modbus protocol is a subset of the protocol as described in the Modicon Modbus Protocol Reference Guide PI MBUS 300 Rev F Only the RTU version of the protocol has been imple mented Modbus RTU mode communicates in standard NRZ asynchronous format with one start bit eight data bits one parity bit and one stop bit Even and odd parity is supported If no parity is specified the number of stop bits can be user configured for either one or two stop bits Baud rates supported at this time are 300 600 1200 2400 4800 9600 19 200 38 400 57 600 and 115 200 baud Modbus uses RS 485 for multidrop communications RS 232 is supported for one module per serial port Modbus is a registered trademark of AEG Modicon Inc The Modbus protocol transmits data 8 bit binary bytes not ASCII To illustrate the data in this document the 8 bit byte is described as two hexadecimal nibbles For example the binary byte value 0101 1101 willbe written as 5D A typical Modbus RTU command may look like this 01 04 0000 0001 31CA Remember this command string and others throughout this docu ment are actually transmitte
57. ications 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 to provide a ground return for the communications loop The D1711M D1712M modules are protected against power supply rever sals The H1750M H1770M boards are powered by 5Vdc 0 25V 30mA max not including any I O module requirements Chapter 8 Troubleshooting Symptom 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 between 10 and 30Vdc 2 Verify using an ohmmeter that there are no breaks in the communica tions 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 If you are using a serial communications converter 1
58. id 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 BYTE 3 FUNCTION XU ATA BIT 6 X x A gt lt 5 NOT USED X NO ECHO 0 ECHO 1 NO DELAYS 2 BYTE TIME DELAYS 4 BYTE TIME DELAYS 6 BYTE TIME DELAYS 00 SetUp Command 5 8 Byte 4 Event Counter Filter The D1711M 1712M contains a programmable digital filter to control the bandwidth of the Event Counter The filter is particularly useful when the Event Counter is used to count transitions from switches or other electro mechanical contacts The filter will debounce noisy signals to provide error free transition counting The filter constant is controlled by bits 4 and 5 of byte 4 The selections are shown in Table 5 4 If no filter is selected the Event Counter bandwidth is 20kHz This setting is ideal for electronic signals with clean transitions To debounce noisy signals filter constants of 5 20 and 50ms are available The operation of the digital filter is described in Chapter 2 Word Length The 1700M command set is used by many digital I O devices ranging from 1 to 64 I O lines Many of the commands such as the DO DI and RA commands operate on all of the data lines in parallel The word length setup is used to adjust the amount of hex bit data transmitted to and from the 1700M device One word of data is defined to be eight bits represented by two hexadecimal digits
59. inated altogether The 1700M series include D1711M 1712M 15 channel I O modules H1750M 24 channel I O board H1770M 64 channel I O board Getting Started The instructions in this chapter cover all 1700 models however for simplicity we use the D1711M amp D1712M in the figures If you have an H1700 board see the appropriate appendix for instructions on getting started Default Mode All models contain an EEPROM Electrically Erasable Programmable Read Only Memory to store setup information The EEPROM replaces the usual array of switches 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 settings There Getting Started 1 2 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 communications with a module whose address and baud rate are unknown To overcome this each module has an input pin labelled DEFAULT By connecting this pin to Ground the modul
60. ion is a periodic burst of data from all the modules without the need for polling by the host The data stream from this system would typically look like this 1DI1234B2 2DI0001AA SDIFFFF02 Each data string is terminated by a carriage return Note that the module address is transmitted with the data to easily determine the origin of the data Continuos Input Output 6 9 The easiest way of setting up a system like this is to install the modules and operate them as a polled system first Once the wiring and the operation of all the modules is established the string may be set for Continuous Mode First set up all the Edge Triggered modules as described in Example C The last step is to setup the Timer module as described in Example A The CT time specified in the Timer module must be long enough to allow all the modules to respond If the CT time is too short module 1 will start to output data before module 3 has finished resulting in communications collision In some cases especially if a large number of modules are connected in a string the amount of data transmitted may overload the serial port buffer of the host In this case the data may be slowed down by specifying a finite amount of time in the Continuous Timer of each edge triggered module A module in Edge trigger mode will delay the output data after it is triggered by the amount specified in CT The host may disable the continuous output data by sending a Continu
61. isfy 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 itis inherently a half duplex system RS 485 offers many advantages over RS 232C 1 balanced line gives excellent noise immunity 2 can communicate with modules at 38400 baud 3 communications distances up to 4 000 feet 4 true multidrop modules are connected in parallel 5 individual modules may be disconnected without affecting other modules 6 up to 32 modules on one line 124 with repeaters 7 no communications delay due to multiple modules 8 simplified wiring using standard telephone cable Communications 3 7 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 interface converters to convert RS 232C to RS 485 These converters also include pow
62. l 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 will break the chain 2 All modules must be plugged into their 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 1700M unit 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 will 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 Communications 3 5 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
63. l notation A logical 1 indicates that an I O line will be configured as an output A logical 0 specifies a data input The length of the hex data argument will vary according to the number of I O lines available and the word length that is setup in the device see Setup section This command configures 16 bits of I O lines to be outputs Command 1 AlOFFFF Response This command configures 23 lines to be inputs and the LSB as an output Command 1A10000001 Response 3 Up to 64 I O lines may be configured at once Command 1AIOF01234AA5500FF88 Response The form of the AIO command requires an ACK to complete the direction assignments see ACK command The AlO command stores the data direction assignments in EEPROM so that the I O lines are configured automatically when the device is powered up The AIO must be preceded by a Write Enable WE command Command Set 4 17 Clear Bit CB Clear Position CP Set Bit SB Set Position SP The Clear Bit command is used to turn off a single output bit The CB command uses hexadecimal notation to address the desired bit Command 1CBOA Response In this case the hexadecimal bit number OA is turned off No other bits are affected Ifthe CB commandis used with the prompt an ACK commandis required to complete the command For example Command 1CB1F Response 1CB1F57 In this case the module has echoed the command along with the resp
64. ll respond with a SYNTAX ERROR and the command will be aborted For example Command 1DI no checksum Response 8000 Command 1DIE2 with checksum Response 8000 Command 1DIAB incorrect checksum Response 21 BAD CHECKSUM Command 1DIE one extra character Response 21 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 101 short form Response 8000 Command 101 long form Response 1DI8000B0 BO 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 ofthe 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 1DOFF00 Command Set 4 12 Characters 1DO F FOO ASCII hex values 23 31 44 4F 46 46 30 30 Sum hex addition 23 31 44 AF 46 46 30 30 103 The checksum is D3 hex Append the characters D and 3 to the end of the message 1DOFFOOD3 Example Verify the checksum of a module response 1DI8000B0 The checksum is the two characters preceding the CR BO Add the remaining character values 1 D 8 0 0 0 2A 31 444 49 38 30 30 30 2 1BO
65. 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 modules with RS 485 outputs are setup atthe factory to provide two units of communications delay after a command has been received see Chapter 5 This delay is necessary when using host 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 Communications 3 9 Black 5 Ri Red Green iko v Yellow Up to 4 000 Feet DO Y HOST 220n R5 485 Bo a GND E LOCAL POWER SUPPLY GROUND zalan 9 HH LHOCT Figure 3 27A5 485 Network 2200 Chapter 4 1700 Command Set Introduction The 1700M series uses Modbus RTU protocol for communication and the 1700M ASCII protocol for setup configuration and default settings The begining of Chapter 4 explains the Mobus RTU protocol usable 1700M Modbus function codes and
66. m would be 1DI8123B6 is checksum 2DIAOAO0CB CB is checksum Module 3 is set for Continuous Input mode with the Continuous Input Address CIA equal to ASCII 31 or character 1 This module will pick off the output data from module 1 and use the data as a command to set its output lines Module 3 will ignore the data from module 2 Module 4 is set for Continuous Input mode and its Continuous Input Address CIA is equal to ASCII 32 or character 2 It examines the data on the communications bus and responds only to data containing the address 2 Therefore the outputs of module 4 will follow the inputs of module 2 In theory up to 124 pairs of modules may be linked together on a single communications bus Continuos Input Output 6 16 Bidirectional Continuous Input Output To provide bidirectional data transfer from one location to another simply use two pairs of modules and two communications links Figure 9 CONTINUOUS INPUT CIA 31 INPUTS OUTPUTS OUTPUTS INPUTS CONTINUOUS CONTINUOUS INPUT OUTPUT ClA 31 J Multiple Outputs The output data from a Continuous Output module may be used to control more than one continuous input module by assigning the correct Continuous Input Addresses CIA Figure 10 CONTINUOUS CONTINUOUS CONTINUOUS CONTINUOUS OUTPUT INPUT INPUT INPUT IMPLITS OUTPUTS OUTPUTS OUTPUTS Continuos Input Output 6 17 In this system module 1 is set for
67. mand response sequence This method is useful when the host is required to produce an output response to a change in the input status The host may control the digital output lines in this case BOO BO7 with normal I O commands After the control function is completed the D1712M may be returned to Continu ous Mode with the CMC command Continuos Input Output 6 11 The change modeis ideal in applications where the state of the digital inputs is expected to change infrequently Inputs such as security switches fire detectors alarm switches etc are not expected to change but must be detected by the host computer By using a D1712M in change mode the host may be alerted to a change in input status on an interrupt basis thereby saving computer time scanning inputs that are static F Change Mode With Multiple Modules Figure 6 It is possible to configure two or mode modules to Continuous Output Change mode on the same serial port This configuration may be used to extend the number of inputs monitored The one drawback to this connection is that there is no means of avoiding acommunications collision if two modules attempt to output data messages at exactly the same time This will result in communications errors Theoretical considerations aside this type of connection may be very useful if the following guidelines are adhered to 1 The inputs being scanned are primarily static This is usually the case when monitoring security an
68. mmand 1CE Response Note When the events Counter reaches 9999999 it stops counting A CE or EC command must be sent to resume counting See also the Events Read amp Clear EC command Continuous Input Address CIA The CIA command is used to specify the input address of a Continuous Input module The address is specified as a two character code indicating the ASCII equivalent of the address character Command 1CIA41 Response In this example the input address is specified as ASCII 41 which is the code for character A If the module is set to Continuous Input mode it will respond to data strings containing address A The Continuous Input Address should not be confused with the polled address as specified with the Setup SU Command Refer to Chapter 6 for specific uses of the CIA command An attempt to set the CIA address with the same value of the polled address will result in an ADDRESS ERROR response The Continuous Input Address is stored in non volatile memory The CIA command must be preceded with a WE command The address value may be read back with the Read Input Address RIA Command Command Set 4 19 Continuous Mode Change CMC Continuous Mode Disable CMD Continuous Mode Edge CME Continuous Mode Input CMI Continuous Mode Timer CMT The Continuous Mode Commands are used to select and enable Continu ous Modes as described in Chapter 6 Only one mode may be selected at any time
69. modes They are listed here for quick reference A more complete description of each command may be found in the Chapter 4 1CMD Continuous Mode Disable 1CMT Enable Timer Triggered Continuous Output Mode 1CME Enable Edge Triggered Continuous Output Mode 1CMC Enable Change Triggered Continuous Output Mode 1CMI Enable Continuous Input Mode 1RCM Read Continuous Mode Type Response is D T E C for Disabled Timer Edge Change or Input respectively 1CT Specify Continuous Timer value in seconds 1RCT Read Continuous Timer 1CIA Specify Continuous Address 1RIA Read Continuous Input Address Continuous Output Trigger Signal In order to facilitate daisy chaining of continuous output modules each module will produce an output trigger signal each time it completes an output data string The output trigger is a 5 millisecond low pulse which appears on the Default pin The Default pin is normally an input pin used to place the module in a known communications setup This is also true when a module is set for Continuous Mode However when a module produces a continuous output the Default pin momentarily becomes an output and produces a low going trigger pulse This trigger pulse may be used to trigger another module set in Edge trigger mode In this manner many modules may be daisy chained together in continuous mode Applications There is a wide variety of system configurations which may be implemented with the contin
70. n that the digital device is powered up and running It also serves to reset the Watchdog Timer see the WT commana Since the RD command is the most frequently used command in a system a special truncated form of the command is available to speed up scanning rates If a module is addressed without a command the RD command is assumed by default Command 1 Response 99999 99 Read Event Counter RE The RE command reads the number of events that have been accumulated in the Events Counter The output is a seven digit decimal number Command 1RE Response 0000107 The maximum accumulated countis 9999999 When this countis reached the Events counter stops counting The counter may be cleared at any time with the Events Read amp Clear command EC or the Clear Events command CE The Event Count is cleared to zero upon power up The Remote Reset RR does not affect the Event Count When reading the Event Counter with a checksum be sure not to confuse the checksum with the data Read Identification The Read IDentification RID command reads out the user data stored by the IDentification ID command The ID and RID commands are included as aconvenience to the user to store information in the 1700M s nonvolatile memory Command 1RID Response BOILER ROOM example Command 1RID Response 1RIDBOILER ROOM54 example Command Set 4 27 In this case the RID command has read back the message BOILER ROOM
71. nction of the unit s word length setup see Setup chapter It is possible to read up to 64 channels Command 1DI Response 00FFOOEEO0CC 1234 The rightmost hex digit always represents the least significant bits BO B3 If the version of the command is used do not confuse the checksum with the digital data Digital Output DO The Digital Output command is used to specify the output data to all outputs at once Command 1DO00FF Response In this example 16 bits of output data are specified in parallel The FF data commands the least significant eight bits BOO to B07 to turn on The 00 data turns off the next eight bits B08 to BOF This command is appropriate for devices setup for two words of data The hex data length specified in the DO command must match the word length setup in the 1700M or else the device will send a SYNTAX ERROR The following command example may be used with a device set up for eight words Command 1D01234567890ABCDEF Response See the Setup chapter for word length description Command Set 4 21 If the DO command is used with the command prompt ACK command is required to complete the output function see ACK command I O lines assigned to be inputs will ignore data sent by the DO command No error message will be generated by outputting data to input channels using the DO command Events Read amp Clear EC The EC command is used to read the value of
72. ny 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 SYNTAX ERROR will result if the structure of the command is not correct This is caused by having too few or too many characters 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 can range from 0 WRITE PROTECTED Allcommands 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 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 m
73. o set up the initial output conditions First it reads the I O direction data previously specified with the assignment commands Then it reads out the Initial Value and performs an internal Digital Output command Therefore the digital outputs are set to a known value upon startup The Initial Value is specified with hex data Command 11VOOFF Response id Modbus RTU Enable MBR To place any 1700M unit into Modbus protocol mode use the Modbus RTU MBR command The MBR command must be used to specify the Modbus device address and enable the Modbus protocol mode The device address consists of a two character hexadecimal value and is stored in EEPROM The two byte address specified is translated to a one byte 8 bit address required by the Modbus protocol The example below can be used to specify a Modbus device address of 01 Command 51 1 Response Command 1MBR01 Response 1MBR019D After the Modbus address is specified a reset is necessary to activate the Modbus protocol mode The reset may be accomplished in one of three ways 1 Removing power for about 10 seconds to perform a power up reset 2 Momentarily grounding the Default pin 3 Issue a Write Enable WE command followed by a Remote Reset RR command After a reset is performed the module is in Modbus protocol mode Command Set 4 23 Modbus Disable MBD The Modbus Disable MBD command is used to disable the Modbus protocol Any 1700M series unit
74. odule 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 opened 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 RSU The following options can be specified by the SetUp command Channel address 124 values Linefeeds Parity odd even none Baud rate 300 to 115 200 Echo Communication delay 0 6 characters Word length 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 SetUp Command 5 2 A typical SetUp command would look like 1SU31070102 Notice that each byte is represented by it
75. of Write Protected Commands These commands are used to alter setup data in the module s EEPROM These commands 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 of course 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 25 printable characters If a properly addressed module receives a command message of more than 25 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 D1700 module begin with either an asterisk ASCII 2A or a question mark 7 ASCII 3F prompt The prompt indicates acknowledgment of a valid command The prompt precedes an error message All response messages are terminated with a CR Many commands simply return a single character to acknowledge that the command has been executed by the module Other commands send data info
76. onse checksum 57 At this point no output action has taken place The purpose of the response message is to allow the host to examine the command received by the module Thus the host may verify that the command was received without error Once the host is satisfied with the response data it may activate the command by responding with an Acknowledge command Command 1ACK Response 5 At this point the output bit B1F in this case will be turned off The CB command will be executed only if the addressed bit has been previously assigned to be an output An attempt to clear an input bit will result an OUTPUT ERROR message and the command will be aborted The bit direction may be assigned with the Al AO and AIO commands An attemptto clear a bit which does not exist will result ina VALUE ERROR indicating an incorrect bit address Toverify the results of a CBcommand the output bit value may be read back with the Read Bit RB command Command Set 4 18 The Set Bit SB command operates exactly like the CB command except that the addressed bit is turned on The Clear Position CP and Set Position SP commands are similar to the CB and SB commands except the desired bit is specified with a decimal address The following two commands perform exactly the same function Command 1SBOF Response Command 1SP15 Response Clear Events CE The Clear Events command clears the event counter to 00000000 Co
77. ontrol the digital outputs in response to the input data or some other control decision It is not necessary to disable the continuous mode before issuing the output command However to avoid communications collisions the host command should be timed to avoid the continuous response from the D1712M The easiest way to do this is to wait for a continuous output string from the module and then immediately issue the output command Another method of performing output functions is to disable the Continuous Mode by issuing a Continuous Mode Disable CMD command The D1712M now acts normally and any of the I O commands may be per formed The Continuous Mode may be resumed with a Continuous Mode Timer CMT command C Edge Trigger Mode With Host The D1712M may be triggered by an external digital signal which will command the D1712M to read the status of the I O lines and report the data Figure 2 HEN The external trigger signal is connected to the BOO EV pin of the module Since the BOO pin is used for the trigger it is not available for general purpose I O in this application The trigger input is designed to accept a TTL level signal although it will withstand a 0 30V input without damage The input may be triggered with a switch by adding a pull up resistor Figure 3 Continuos Input Output 6 6 10K EGEY E The module is triggered on a positive going edge to the BOO EV pin To setup the D1712M for edge trigger mode
78. orm responses are used in cases where the hostwishes 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 1DI short form Response 8000 Command 101 long form Response 1DI8000B0 BO checksum For the 1700M commands that affect the digital outputs the form of a command starts a handshaking sequence that must be terminated with an Acknowledge ACK command See ACK command Checksum The 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 Set 4 11 Command Checksum A two character checksum may be appended to any command to the 1700M series 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 will calculate the checksum for the message If the calculated checksum does not agree with the transmitted checksum the module will respond with a BAD CHECKSUM error message and the command will be aborted If the checksums agree the command will be executed If the module receives a single extra character it wi
79. ormation Command 1SU31070102 Response Command 1SU31070102 Response 19U3107010291 Command Set 4 30 Watchdog Timer WT The Watchdog Timer WT command stores a data value in EEPROM specifying the time out value of the watchdog timer The time data is scaled in minutes Command 1WT 00010 00 Response 1WT 00010 00 Response 1WT 00010 00B0 These two command examples set the watchdog time value to 10 minutes In this example if the module does not receive a valid command for a period of 10 minutes the digital outputs will automatically be forced to the Initial Value The purpose of the Watchdog Timer is to force the digital outputs to a known safe value in the event of a host or communications link failure The Initial Value is set with the command The watchdog timer may be disabled by setting the timer value to 99999 99 WT command data less than 16 minutes will result in a VALUE ERROR The WT command is write protected The watchdog timer may be used in Continnuos Input mode Write Enable The Write Enable WE command must precede commands that are write protected This is to guard against accidentally writing over valuable data in the EEPROM To change any write protected parameter 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 pro
80. ous Mode Disable command to the timer module Command 1CMD Response 1CMD2F The host should repeat the CMD until the proper response is obtained After the timer mode is disabled the string of modules may be polled by the host To return to continuous output operation enable the continuous mode of the Timer module Command 1CMT Response Change Mode Figure 5 Continuos Input Output 6 10 A D1712M module set up for change mode will output a data string if one of its digital input lines has changed state The module will output the data string reporting the new state of the inputs To setup the D1712M for change mode Assign the desired I O lines to inputs Command 1AIOO0FF Response Note that not all lines are required to be inputs In this example digital I O lines B00 BO07 are set to outputs and B08 BOE are set to inputs For this example set the Continuous Timer to zero Command 1CT 00000 00 Response Set the module to Continuous Mode Command 1CMC Response The D1712M will continually scan the Digital I O lines to detect any changes of state If a change is found the new state of the I O lines is reported to the host 1DIO1FFD5 After the response is transmitted the D1712M will resume scanning the l O lines The host may disable the continuous output mode by sending a CMD command Command 1CMD Response 1CMD2F The module may now be interrogated with the normal com
81. p RS 485 Quick Hook Up Software is not required to begin using the 1700M series 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 Putthe 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 101 and pressing the Enter or Return key The module will Getting Started 1 3 respond with an followed by the data reading at the input orar godo 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 thatincludes a channel address of 1 300 baud rate no linefeeds no parity no echo and two character delay Refer to the Chapter 5 to configure the module to your application 10 to 30 de Power Supply 012117 DIGITAL ICO DEFAULT pcos BAA TRANSMIT BAB HQ Pg Ye E S HQ PQ AE Note Fusing DE 25 connector ground is tied to pin 7 Pin tied to TRANSMIT and pin 2 is tied to RECEIVE on the module Figure 1 1 RS 232 Quick Hook Up Getting Started 1 4 BIE REE Bey E RIE REED ES
82. position to select RS 485 If RS 232 is selected the DATA TX pin on the 6 pin connector is the transmit output pin The DATA RX pin is the receive input If RS 485 is selected connect the Data Data line to the DATA TX pin and the Data Data line to the DATA RX pin The H1750M is powered by a regulated 4 75 to 5 5V power supply connected to the GND and 5 Vdc pins For proper operation relays used in a backplane should be 5V types I O lines are connected to the odd numbered pins on the header connector The odd numbered pins are closest to the edge of the board with the square pad being 1 All even numbered pins are connected to ground Pin Connections The host interface connection is wired to the six pin terminal plug Pin 1 5V This is the power supply connection for the board The power supply must provide 5V 5 at 100 mA Pin 2 DEFAULT This is normally left open or pulled high to 5V When grounded the board assumes the default communications setup of 300 baud any address no parity See Chapter 1 Pin 3 DATA TX This pin is a serial port connection If the board is configured for RS 485 this pin is the DATA connection For RS 232 pin 3 is the Transmit output from the H1750 Pin 4 DATA RX This pin is a serial port connection If the board is configured for RS 485 this is the DATA or the negative data connection H1750M C 2 For RS 232 this is the receive input of the H1750M Pin 5 CONT
83. previously stored by the ID command See ID command Read Initial Value RIV The Read Initial Value command is used to read back the Initial Value stored in the EEPROM The Initial Value is the output data used to initialize the 1700M upon power up The Initial Value is set with the Initial Value IV command Command 1RIV Response OFOF The length of the hex data returned is dependant on the specific 1700M model and the number of words in the setup see Setup chapter Read Modbus Address RMA The Read Modbus Address command is only used for toubleshooting purposes The RMA command tells you if the Modbus protocol is enabled or disabled and the Modbus slave address in the module This command should only be used when the module is in the DEFAULT mode Command 1RMA Response 0001 Command 1RMA Response 1RMA0001FC The response contains two bytes The second byte contains the Modbus slave address in this example 01 The first byte indicates whether the Modbus protocol is enabled or not enabled In this example 00 indicates that the Modbus protocol is not enabled If the first byte were 01 the Modbus protocol is enabled Read Input Bit RIB Read Input Position RIP The Read Input commands are used to read the logical state of individual I O lines The desired line is specified with either Bit or Position addressing Command 1RIBOF Response 1 The module will respond with a 1 ora 0 indicating the state
84. r are thoroughly checked for syntax and data errors Valid commands are then processed to complete the desired function A wide variety of commands are available to configure and control the digital I O Functional Description 2 2 lines Responses to the host commands are then produced by the micro processor and transmitted back to the host over the RS 485 serial link An Electrically Erasable Programmable Read Only Memory EEPROM is used to retain important data even if the module is powered down The EEPROM contains setup information such as the address baud rate and parity as well as I O configuration data Each digital line on the D1712M is bidirectional and may be individually configured by the user to be an input or an output The direction assign ments of all the lines are stored in EEPROM so that the lines are automatically configured each time the D1712M is powered up HY HY Fl Ez 1711 1712 100K Open 1750 1770 22k 10k pe IMPLIT 140 BIT pe OUTPUT GND Figure 2 2 Digital I O Circuit Figure 2 2 is a detail diagram of a single I O line circuit The output driver is a darlington circuit capable of sinking 100mA with a maximum output voltage of 30V The maximum total current that may be handled by the D1711M or D1712M package is 1A The output saturation voltage at 100mA is 1 2V max Pullup resistors are not provided in the modules When the I O pin is configured as an input the output driver is turned off
85. r input The filter is necessary when the event signal is derived from mechanical contacts such as switches or relays The filter constant is user selectable for 0 5 20 or 50ms Figure 2 5 shows the filter action for the 5ms setting EVENT COUNTER SAMPLE CLOCK FILTERED SIGNAL AE IA Figure 2 5 Event Counter Debounce Filter The microprocessor samples the event input at 1ms intervals The input signal must be high for at least five consecutive samples before it will be Functional Description 2 5 counted as a high transition Similarly the input must be low for five sample periods before itis counted as a low signal If the filter is set for 20ms the input must be stable for 20 consecutive samples etc The last major block in the diagram is the power supply The power supply converts the raw 10 to 30 volts supplied by the user into regulated voltages used in the module It produces 5V necessary to operate the microproces sor and EEPROM On RS 232 units the power supply produces 10V necessary for the RS 232 communications standard Chapter 3 Communications Introduction The 1700M series 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
86. r of physical I O bits At the factory the D1700M is configured such that all the physical I O bits are available for use The Setup Message contains a user selectable variable called Word Length that determines how many bytes of physical I O bits are avail able Word Length values from 1 8 are possible indicating 8 64 indi vidual bits in the product being used Since this value is user selectable it is possible to set the D1700M such that the number of I O bits is less than the physical quantity Modbus Address Exception error codes will be returned when attempting to turn On or Off a bit whose address is higher than the quantity of bits enabled in the Setup message 06 Preset Single Register Function 06 is used to write values to a Modbus register in the D1700M This function is used to control two features in the D1700M There is a single register in the D1700M that will accept values using this function Register 40001 is used to controls specific functions in the D1700M A list of values and their functional definitions are listed below Values Functional Definition 00 Suspend the Modbus Protocol to DGH ASCII protocol at Baud Rate and Parity type specified in the Setup mes sage SU 01 Clear Events Counter on D1711M or D1712M Modbus Exception error returned on H1750M and H1770M Command Set 4 5 15 Force Multiple Coils This function controls multiple coils or digital output bits in a D1700M mod
87. rmation following the prompt The response format of all commands may be found in the detailed command description The maximum response message length is 25 characters Command Set 4 10 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 performthe desired function andthe communicate the response backto 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 an appropriate amount of time specified in Table 3 1 a communications time out error has occurred After the communications time out itis 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 the module will respond with a long form response This type of response will echo the command message supply the necessary response data and will add two character checksum to the end of the message Long f
88. rs For example using a D1711M that contains 15 physical I O bits a Modbus Data Address Exception will be returned if a host tries to read or modify any bit value higher than 15 03 Illegal Data Value This Modbus Exception error code is returned when attempting to write a register value that is not supported For example using Modbus Function 06 attempting to write a value of 02 or higher will result in a Modbus Data Value Exception as that value is not supported D1700M Modbus Register Map Register Description Values Notes 40001 Control Register O 1 0 Suspend Modbus Return to DGH ASCII 1 Clear EventsCounter 40002 EV Counter HI Byte 0 0098 16 bit unsigned value 40003 EV Counter LO Byte 0 FFFF 16 bit unsigned value The 1700 series operate with a simple command response protocol to control all module functions Acommand mustbe 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 unless it is setup for Continuous Output Mode see Chapter 6 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 Set 4 7 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 two valid prompt
89. s Command 2CIA31 Response The input address 31 is stored in nonvolatile memory It can be read back with the Read Input Address command Command 2RIA Response 31 4 Enable the Continuous Input Mode with the Continuous Mode Input command Command 2CMI Response The Continuous mode is saved in nonvolatile memory After the Continuous Input module has been setup it may be connected to the continuous output module as a stand alone pair Since all setup data is stored in nonvolatile memory the input output pair will initialize automati cally upon power up No host is necessary for the continuous input output function Continuos Input Output 6 15 H Multiple Continuous Input Output Figure 8 shows a system with two modules set for continuous output mode and two modules set for Continuous Input Mode Figure 8 INPUTS OUTPUTS CONTINUOUS CONTINUOUS OUTPUT INPUT Note When using H1750M or H1770M Digital I O boards in a multiple continuous application the Default line from the preceding board or module must be connected to the Cont terminal instead of BOO This system is similar to example E except that 2 input output module pairs share the same communications line Modules 1 and 2 are setup for continuous output as detailed in example B This pair of D1712M s con stantly read the state of their respective digital I O lines and output the data on the communications bus A typical output data strea
90. s 0 10V 15mA max load Power requirements 5Vdc 0 25V 30mA max not including I O modules requirements User selectable RS 232 RS 485 Communications D1700M Digital Input Output Modules D1711M 15 digital input output bits with RS 232 output D1712M 15 digital input output bits with RS 485 output User can define any bit as an input or an output Input voltage levels 0 30V without damage Input switching levels High 3 5V min Low 1 0V max Outputs Open collector to 100mA max load Vsat 1 0V max O 100mA Events counter Up to 10 million positive transitions at bandwidths of 20Hz 50Hz 200Hz and 20KHz Power requirements Unregulated 10V to 30Vdc 0 75W max Internal switching regulator Protected against power supply reversals Communications Communications in ASCII via RS 232 RS 485 ports Up to 124 multidrop boards per host communications port User selectable channel address NRZ asynchronous data format 1 start bit 7 data bits 1 parity bit and 1 stop bit Selectable baud rates 300 600 1200 2400 4800 9600 19200 38400 56700 115200 ASCII format command response protocol Can be used with a dumb terminal Parity odd even none 1700M Specifications D 2 All communications setups address baud rate parity stored in nonvolatile memory using EEPROM Transient suppression on RS 485 Communications lines Communications error checking via checksum
91. s 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 For the purposes of describing the SetUp command bit 7 refers to the highest order bit of a byte of data Bit 0 refers to lowest order bit bit number 7 0 0 binary data 1 6 5 4 3 2 1 0 1 1 0 0 0 31 hex The SU command is write protected to guard against erroneous changes inthe setup data therefore each SU command must be preceded by a Write Enable WE command To abortan 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 to examine the existing setup data before proceeding with the SU command Byte 1 Byte 1 contains the module channel address The address is stored as the ASCII code for the string character used to address the module In our example command 1SU310
92. s wired to the six pin terminal plug Pin 1 5V This is the power supply connection for the board The power supply must provide 5V 5 at 100 mA Pin 2 DEFAULT This is normally left open or pulled high to 5V When grounded the board assumes the default communications setup of 300 baud any address no parity See Chapter 1 Pin 3 DATA TX This pin is a serial port connection If the board is configured for RS 485 this pin is the DATA connection For RS 232 pin is the Transmit output from the H1770M Pin 4 DATA RX This pin is a serial port connection If the board is configured for RS 485 this is the DATA or the negative data connection For RS 232 this is the receive input of the H1770M H1770M B 2 Pin 5 CONT This pin is normally left open or pulled up to 5V When grounded the H1770M will be in Continuous Mode When using H1750M or H1770M Digital I O boards in a multiple continuous application the Default line from the preceding board or module must be connected to the Cont terminal Pin6 GND This is the power supply ground connection Itis also the signal ground for the serial port Output Connections The digital I O connections are made through the four ribbon cable connectors The output connections are made to be compatable with industry standard 16 channel solid state relay racks The connector near est the edge of the board J2 is wired to the lowest order 16 bits J2 Pin Signal 17 BOF
93. sible indicating 8 to 64 individual bits in the product being used Since this value is user selectable it is possible to set the 1700M such that the number of I O bits is less than the physical quantity Modbus Address Exception error codes may be returned if attempting to read more bits than the setup message indicates are available There fore ensure that the first bit address and the combined quantity of bits to read are within the number of bits enabled in the Setup message 03 Read Holding Register This function will read the Events Counter value in the D1711M and the D1712M modules When digital bit BOO is configured as a digital input then it will count positive transitions and store them in a counter register The Events Counter value ranges from 0 9 999 999 counts This value is returned in two 16 bit unsigned integer words The HI word is located in register 40002 and the LO word is located in register 40003 Note Attempts to read these values from an H1750M or H1770M board that do not contain an Events Counter will result in an Invalid Function Modbus Exception error code 01 Command Set 4 4 05 Force Single Coil This function controls coils or digital output bits in a D1700M module or board The bits can be turned On and Off individually using this function The number of physical coils to turn On or Off is determined by the D1700M and the Setup message SU Each D1700M contains a certain numbe
94. tected 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 Command Set 4 31 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 WE command ERROR MESSAGES All modules feature extensive error checking on input commands to avoid erroneous operation Any errors detected will resultin 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 format for either the or prompts For example 1 SYNTAX ERROR There are eight error messages and each error message begins with a different character Host computer software can identify an error by the first character it is not necessary to read the whole string ADDRESS ERROR There are four ASCII values that are illegal for use as a module address NULL 00 CR 0D 24 and 23 The ADDRESS ERROR will occur when an attempt is made to load an illegal address into a module with the SetUp SU command An att
95. 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 D1711M 31070102 D1712M 31070102 H1750M 31070103 H1770M 31070108 1000 Software Setting up your 1700M device may be greatly simplified by using the setup program provided in the utility software package The software runs on IBM PC s or compatibles and is free of charge The setup program provides a menu driven operator interface which greatly simplifies the setup process and decreases the chances of setup errors Chapter 6 Continuous Input Output The 1700M series when used in DGH ASCII mode may be setup in special modes which allow them to communicate without being polled by a host computer Collectively these modes are called Continuous Input Output Modes In many applications the burden on the host may be greatly simplified and in some cases the host may be eliminated altogether Continuous Output A D1711M 1712M in continuous mode will produce an output string in the same format as the response to a 1DI command 1DI8000B0 Note that the output message contains the response prompt the module address 1 the status of the digital I O lines 8000 and a checksum
96. to data transmitted by another module A module in Continuous Input Mode may be paired with a module in Continuous Output Mode to provide digital data transfer without a supervisory host Figure 6 shows the simplest connec tion Figure 7 INPUTS OUTPUT CONTINUOUS CONTINUOUS OUTPUT INPUT TIMER MODE INPUT ADDRESS 1 Continuos Input Output 6 13 Module 1 is setup in Continuous Output Timer Mode as described in Example A Module 1 will read the state of the digital inputs and produce data messages on the communications bus In this application setting the Continuous Timer to zero will produce the fastest response to input changes Module 2 is setup for Continuous Input Mode The digital I O lines of module 2 are assigned as outputs In continuous input mode module 2 will use the data from module 1 as a command to control the digital outputs The net effect is that the outputs of module 2 are controlled directly by the inputs of module 1 For example an output message from module 1 might look like 1DIA0A059 59 is checksum Module 2 in Continuous Input mode will interpret this data as a Digital Output command Internally the continuous input module will translate this data and perform the same function as 1DO5F5FAD AD is checksum Note that the original data AOAO is complemented to 5F5F This is necessary so that a high input at module 1 appears as a high output at module 2 As a result the state
97. tocol mode using the MBR command Disable the Modbus RTU mode using the Modbus Disable command Windows Quick Start Steps 1 Locate the DGH Utility Software CD ROM and place it in your computer CD ROM drive 2 Using Windows systems click on the Start button in the lower left hand corner When the menu pops up select Run and the Browse to the CD ROM drive in your machine 3 Selectthe Setup exe file and Run it This will begin installation of the DGH Windows Utility Software 4 The installation program will run and you can select the default instal lation settings by pressing the Next button thru most of the prompt screens 10 11 12 13 14 15 16 17 E etting Started 1 6 Once the installation is completed you can review the ting platted file Or simply Finish the process A Utility Software icon will be placed on your Windows desktop Click on this icon to run the Utility Software All DGH Users Manuals were installed during the Utility Software installation process The Users Manuals can be found on a new menu by pressing the Windows Start button and selecting Programs Next select DGH Data Acquisition and then select Manuals Click on the 1700M Users Manual to open it Connect a power supply to the D5000M between the VS terminal and the GND terminal The power supply voltage must be between 10 and 30Vdc Prop
98. tween computing equipment RS 232C versions of the 1700M series 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 this system allows for several modules to be connected in a daisy chain network structure Note that when used inModbus mode the 1700M series RS 232C is only single station 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 Communications 3 3 However RS 232C suffers from several disadvantages 1 low noise immunity 2 short usable distance 50 to 200 feet 3 maximum baud rate 19200 4 greater communications delay in multiple module systems 5 less reliable loss of one module breaks chain 6 wiring is slightly more complex than RS 485 7 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 multi party system however the D1700 modules can be daisy chained to allow many modules to be con n
99. ucture Many 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 majority of data values used with the 1700M series is in the form of hexadecimal base 16 numbers representing digital data Each hexadeci mal ASCII digit represents four bits of digital data For example E5 hex 1110 0101 binary An example command may look like this Command 1DOFFFF Command Set 4 8 This is an example of the Digital Output DO command This particular command would be used to turn on 16 bits of data represented by FFFF Data read back from the Event Counter with the Read Events RE command is in the form of a seven digit decimal number For example Command 1RE Response 0000123 Analog data is represented in a form of sign five digits decimal point and two additional digits Command 1RWT Response 00010 00 The analog data format is used with the WT and CT commands Bit Addresses There are several commands that are used to manipulate a single bit These commands require a bit address so that the desired action will be directed to the correct I O line Bit addresses may be specified in two different formats the Bit format and the Position format The Bitformat specifies the desired l O line using atwo character hexadeci mal number precede
100. ule or board The output bits can be turned On and Off in groups using this function The number of physical coils or bits in the D1700M is determined by the D1700M in the Setup message SU Each D1700M contains a specific number of I O bits 15 24 or 64 bits At the factory the D1700M is configured with all I O bits available The Setup Message contains a user selectable variable called Word Length that determines how many bytes of physical I O bits are available Word Length values from 1 to 8 are possible indicating 8 bits to 64 bits individual bits Since this value is user selectable it is possible to set the D1700M such that the number of I O bits is less than the physical quantity in the product Modbus Address Exception error codes will be returned when attempting to turn On or Off a bit whose address is higher than the quantity of bits enabled in the Setup message Command Set 4 6 Exception Error Codes 01 Illegal Function This Modbus Exception error code is returned when an un supported function value is received For example if a host controller transmits a Modbus function 07 Read Exception Status code to the D1700M then a 01 error code will be returned as this function is not supported 02 Illegal Data Address This Modbus Exception error code is returned when attempting to address a coil or register value that is not supported or out of physical range of bits and or registe
101. uous mode modules It would be impossible to detail every possible connection However a variety of examples will be given to demonstrate typical usage Continuos Input Output 6 3 A Timer Mode Figure 1 HOST RS 232 In this configuration a D1712M module is set to continuously output data to a host computer or display device It is not necessary for the host to poll the D1712M to obtain data The host computer must have an interrupt driven serial input for proper operation For this example we will setup the D1712M to output data every 10 seconds WE commands are not shown but necessary for write protected commands 1 Setup the D1712M as usual with the setup SU command for correct communications to the host Command 1SU31070102 Response 2 Assign the I O lines of the D1712M to be inputs Command 1A100000 Response 5 3 Set the Continuous Timer CT for a 10 second interval Command 1CT 00010 00 Response This tells the D1712M to output data continuously in 10 second intervals Continuos Input Output 6 4 4 Activate the continuous output with the Continuous Mode Timer CMT command This will activate the continuous output data 5 Every 10 seconds the D1712M will read the status of its I O lines and output the status of those lines as if it was responding to a 1D1 Command Response 1DI1234B2 6 The Continuous Mode may be disabled by the host by sending a Continuous Mode Disable command
102. utput Bit AOB Assign Output Position AOP The Assign Input and Assign Output commands are used to specify the data direction of an individual I O line The Assign Input commands configure an individual bit to be used as an input to read external signals The Assign Output commands configure data bits to be outputs to control external equipment This command configures Bit 05 to be an output Command 1AOBO05 Response This command configures Bit OC to be an input Command 1AIBOC Response When used with the prompt the Al AO commands require ACK command from the host to complete the bit assignment Command HAIBOC Response 1AIBOC9A Command 1ACK Response e See Acknowledge ACK command for more detail The Assign Input Position AIP and the Assign Output Position commands Command Set 4 16 operate in the same manner as the AIB and command except that the bit positions are specified in decimal base 10 notation All of the Assign commands alter the contents of the EEPROM and therefore must be preceded by a Write Enable WE command The I O direction assignments altered by the Assign commands are saved in EEPROM so that all pin directions are automatically configured when the device is powered up Assign Input Output AIO The Assign Input Output AIO command is used to configure the data direction of all data lines at once The direction data is represented in hexadecima
103. values that need to be changed are the Baud Rate possibly the Parity type and the Modbus Slave Address Most Modbus systems use No Parity Getting Started 1 7 18 Set the Baud rate to the same baud rate as the Modbus Master device that this module will be connected to 19 Select the new Modbus Slave address and check the Enable box Then press the Apply button to download the changes to the module The setup is complete Modbus Installation Verification 1 The DGH module is now configured for the proper Baud Rate and Modbus Slave Address The module can now be connected directly to the Modbus Master Or it can be functionally checked 2 To functionally verify the operation of the Modbus protocol make sure that the Default terminal is no longer connected to the GND terminal 3 From the Utility Software main menu select Tools and then select Evaluation Screens and then Modbus I O Screen 4 Click on the Settings button and change the Baud Rate to the value that the module is configured for 5 Press the Advanced button Select 8 Data bits RTS Only No Parity and 2 Stop Bits Press the Update or Open button 6 Select the Modbus Slave Address to the same value as the module is configured for Select Modbus function 04 and register O00 Press the Transmit button Hexadecimal numbers will appear in the Response box These
104. y represent a percentage of the full scale value If your getting readings back that move as your input moves then the Modbus protocol is working successfully For more information on how to compute these values consult the Users Manual for your product For more information on Modbus portocol see Chapter 4 Chapter 2 Functional Description The 1700M Digital I O series provide remote control and monitoring of on off signals in response to simple commands from a host computer Digital commands are transmitted to the 1700M units using standard RS 232 or RS 485 communications links Commands and responses are in the form of simple English ASCII character strings for ease of use The ASCII protocol allows the units to be interfaced with dumb terminals and modems as well as intelligent controllers and computers TRANSMIT DATA 5 485 MICRO OUTPUT INTERF CE RECEIVE PROCESSOR DRIVERS DA COUNTER 10 204 V ho POWER SUPPLY Figure 2 1 Digital I O Functional Block Diagram Figure 2 1 shows a functional block diagram of a D1712M An 8 bit CMOS microprocessor is used to provide an intelligent interface between the host and the bi directional I O lines The microprocessor receives commands and data from the host computer through a serial communications port Special ized communications components are used to interface the microprocessor to the RS 485 communications standard Commands received by the microprocesso

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