DT80 Modbus Master
Contents
1. Modbus read on the serial sensor port Slave address 12 reading a 16 bit signed integer register type 3 register 2 Time out between retries set to 10 seconds Retries RTn Where e n the number of retries to perform following a Modbus master error or timeout Page 10 of 16 TR 0011 A1 datalaker Training Note TR 0011 Note The value must be between 0 and 25 with the default being 0 Example 1MODBUS AD12 R3 2 RT3 Modbus read on the serial sensor port Slave address 12 reading a 16 bit signed integer register type 3 register 2 Three retires with default time out of 1 second Unit ID MUIDn Where e pe the Modbus unit id field Typically used when communicating to a serial slave via a TCP IP connected gateway device Example AMODBUS AD 192 168 1 212 R3 2 MUID12 Modbus read on the Ethernet port Modbus gateway TCP IP address 192 168 1 212 Modbus Unit ID number 12 reading a 16 bit signed integer register type 3 register 2 Assign to Channel Variables m nCV Where e m the first channel variable to assign e n the final channel variable to assign This channel option allows for multiple consecutive reads to be performed from a slave device and stores the result s to a range of channel variables Example 1 IMODBUS AD12 R3 100 1 5CV Read from slave at address 12 register type 3 registers 100 105 into channel variables 1CV to 5CV Example 2 2MODBUS AD12 R4 1 10 15CV Write the value2. Modbus commands Modbus related profile settings Serial Sensor Port PROFILE SERSEN_PORT FUNCTION mode PROFILE SERSEN_PORT FLOW NOFC PROFILE MODBUS_SERVER SERSEN_ADDRESS addr Where e mode can be either o Modbus for Modbus slave mode o Modbus Master for Modbus Master mode e addris 8 bit Modbus slave address in the range of 1 to 247 Notes e Software flow control interrupts the Modbus protocol and thus should not be used Host Port PROFILE HOST_PORT FUNCTION mode PROFILE HOST_PORT FLOW NOFC Where e mode can be either o Modbus for Modbus slave mode o Modbus Master for Modbus Master mode Notes e Software flow control interrupts the Modbus protocol and thus should not be used e The Host Port only supports RS232 and therefore can only be point to point That is only one Modbus slave device and one Modbus master e Use the other Host_Port profile setting to configure the other communications parameters baud rate etc Page 7 of 16 TR 0011 A1 datalaker Training Note TR 0011 TCP IP PROFILE MODBUS_SERVER TCPIP_PORT port Where e portis the TCP IP port number Modbus will use to communicate with the DT80 Default is port 502 Notes e The device address is the TCP IP address or symbolic DNS address With Modbus TCP IP the DT80 acts as both a master and slave Use the Ethernet profile settings to configure network settings Use a static TCP IP address if you don t have a symbolic DNS address for the DT
3. of channel variables 10 to 15 to Modbus registers 1 to 5 Reverse Span SRn Where e n the span number This channel option applies a defined span in reverse Example 1 0 100 4 20 Span to convert 4 20 signal to pressure 1MODBUS AD12 R3 100 1CV S1 read 4 20 value from Modbus 1cV pressure store value as pressure 1MODBUS AD10 R4 10 RS1 1CV write to other device as 4 20 Read a value in from one Modbus device scale and store it then write the value to another Modbus device in original units Page 11 of 16 TR 0011 A1 datalaker Training Note TR 0011 Channel Factor When working with integer data types it is not possible to represent data with decimal places It is common for the Modbus slave device to multiply the value by a scalar ie 10 100 etc then transmit the scaled value The Modbus master device must then divide the read value by the scalar to restore the decimal places Example 1 1MODBUS AD12 MBI R3 1 0 1 Modbus read on the serial sensor port Slave address 12 Register type 3 Input register 1 as a signed integer The channel factor of 0 1 will divide the input by 10 thus restoring one decimal place Troubleshooting Error numbers and messages E124 Modbus transaction failed Modbus communications has failed Check e Communications cabling e Slave device is powered e TCP IP network is active e Software flow control is turned off on both master and slave E125 Modbus write att
4. 5654 scsissccssstsscesncesssiesaasicedsassasnncaavbccessadasvescasscucsessecceseassecdoads 13 Data type range REH eeeeee 13 KEE 14 Programming the DT80 as a Modbus Master Error Bookmark not defined Eeer Error Bookmark not defined Configuring the DT80 as a Modbus master vices sescssccssctevenssvetraccevsuvecnesstvnssevetonenes 14 nn EEN 14 EE dE 14 Implementation crannies E N ep eoeens 16 Page 2 of 16 TR 0011 A1 datalaker Training Note TR 0011 DT80 Modbus Master Introduction Modbus is a simple communications protocol which is widely used in SCADA supervisory control and data acquisition systems Modbus provides an efficient and standardized way to transport digital states and data values between a remote terminal unit RTU or programmable logic controller PLC and a supervisory computer In a Modbus based SCADA system each RTU PLC acts as a Modbus server or slave These servers slaves listen for and reply to requests from a Modbus client or master system A Modbus client is typically a computer that provides a mimic display user interface and various data logging and alarm functions Modbus Master Client capability will be added with the next firmware release after version 7 10 Application The DT80 range having both master and slave capabilities will open new opportunities including e Integration into Industrial SCADA systems e Ability to use a new range of Modbus capable sensors e Real time data exchange bet
5. 80 Modbus master commands channel type and parameters nMODBUS Channel Type The DT80 uses the channel type nModbus to read or write the registers of Modbus slave devices Channel options are used to set the register address data types etc Syntax nMODBUS options value Where e n the Modbus master port the command will be sent out see Table 4 below e options the dataTaker channel options Port Number n Physical connection 1 Serial sensor port 2 Host port 4 Ethernet port Table 4 DT80 range port numbers nMODBUS Channel options Address ADn Where e n address of slave device on serial link 1 2 83MODBUS 1 247 default 1 0 broadcast to all slaves write only Example 1 1MODBUS AD12 R3 2 Modbus read on the serial sensor port Slave address 12 reading a 16 bit signed integer register type 3 register 2 Example 2 2MODBUS AD2 R3 500 Modbus read on the host port Slave address 2 reading a 16 bit signed integer register type 3 register 500 Page 8 of 16 TR 0011 A1 datalaker Training Note TR 0011 Address AD ip_ address Where e ip address is the IP address of slave device on TCP IP network 4MODBUS only Note The IP AddressMay be numeric IP address or symbolic DNS address Example 1 4MODBUS AD 192 168 1 212 R3 2 Modbus read on the Ethernet port Slave TCP IP address 192 168 1 212 reading a 16 bit signed integer register type 3 register 2 Example 2 4MODB
6. MBER C POWER AMODBUS AD 192 168 11 71 R3 5 MBI CHAMBER C AVE 176C 0 1 LOGON END For customer service call 1300 735 292 Thermo Fisher To fax an order use 1800 067 639 SC bei ei ba hp ER cl fa e Visit us online www thermofisher com au 2010 Thermo Fisher Scientific Australia Pty Ltd All rights reserved A B N 52 058 390 917 TR 0011 A1
7. US AD DT80 com au R3 2 MBI Modbus read on the Ethernet port Slave TCP IP address is Modbus DT80 com au reading a 16 bit signed integer register type 3 register 2 Register Rt rrr b Where e t register type one of o O coil o 1 discrete input o 3 input register o 4 output register rrr Register number 1 65536 e b number of digital bits to pack into a single value 1 16 default 1 o Only valid for digital register types t 0 1 Example 1 2MODBUS AD12 R0 8001 0 Modbus write on the Host port Slave address 12 Register type 0 Coil register 8001 If connected to a DT80 this will set digital output 1 to 0 Example 2 2MODBUS AD12 R1 8001 Modbus read on the Host port Slave address 12 Register type 1 Discrete register 8001 If connected to a DT80 this will read the current value of digital input 1 Example 3 2MODBUS AD12 R3 1 Modbus read on the Host port Slave address 12 Register type 3 Input register 1 If connected to a DT80 this will read the current value of 1CV Example 4 2MODBUS AD12 R4 1 600 Modbus read on the Host port Slave address 12 Register type 4 Output register 1 If connected to a DT80 this write 600 to 1CV Example 5 2MODBUS AD12 R0 10 4 16 Modbus read on the Host port Slave address 12 Register type 0 coil register 10 bits 1 to 4 This will set bits 1 to 4 to 1 Page 9 of 16 TR 0011 A1 datalaker Training Note TR 0011 Data Type Format MBxx Whe
8. V gt 0 then output 1 18000 to 18009 Digitals 1 to 8 and 1Relay Returns digital state Register type Comment Holding register is read only Holding register 30001 to 31000 Channel variable 1 to 1000 Returns current CV value 34001 to 34053 System variables 1 to 53 Returns current SV value 38000 to 38009 Digitals 1 to 8 and 1Relay Returns current digital value 0 or 1 Register type Comment Input register is read write Input register 40001 to 41000 Channel variable 1 to 1000 Returns current CV value 44001 to 44053 System variables 1 to 53 Returns current SV value 48000 to 48009 Digitals 1 to 8 and 1Relay Returns current digital value 0 or 1 Table 2 DT80 range Modbus registers with function numbers Note The DT80 range user s manual uses the convention lt Type gt lt Register gt e g 3 0001 to distinguish between the register type and register number instead of the Modbus convention This is to reduce the confusion caused to users new to Modbus As can be seen the first digit of the register number indicates the type of register coil discrete input input register or output register This usage is however just a convention This digit is not part of the actual address transmitted in the Modbus message A further potential source of confusion is the fact that the actual transmitted address is zero based so register number x0003 is actually transmitted as address 0002 Note I
9. datalaker Training Note TR 0011 DT80 Modbus Master Firmware 8 06 October 2010 Page 1 of 16 TROTA datalaker Training Note TR 0011 CONTENTS DT80 Modbus better 3 tee 3 PNG AU EE 3 er 3 Modbus communications methods scicsics cacakidsiecsassesgeideneacetaatssescdsioseeaesneeetananitenciecaeaees 3 Senal E e E 3 TCP IP COMME CU OM ME 4 Modbus register TY DEN i cccacerarssancacisoerarcanectnies ra eate asen stan sadceasrammearemacee era aera 4 Modbus data EE 6 Pl nning a Modb s Task scscsccssaccessnncieesstswenniesssaveasansicarnntesuwnduana sdesssbonvenceesatenawaveneasagnabesssauers 6 DT80 Modbus comm dS ced etegg deeg T Modbus related profile RER 7 Serial Sensor PO EE T Host EE T Ke 8 Modbus master commands channel type and parameterg eee seeeseeeeseee 8 AMODBUS Chann l Eer 8 nMODBUS Channel options scisceisecascarssccsaesacvennteacnaceavancwavansnsdsates ducssemancesetancaseanane 8 E SS in aga e a a das ee a Na a E shag oea aE e 8 Scie eters ce pace oe wes cee essen yo encanta was eee eee ee 9 ter Tye OTA eege ee een 10 Word ety Endla isco cacaciannasslacssenepenernontua achaduasasennsudteatmunanen veda EEEE EEEE 10 UMN E 10 e 10 UMID eee eee E re ee E ee ee 11 Assign to Channel Variables siciscasscccicessscesaasscsednanasstecavaccensssacvescansatedeassaseenasaneancass 11 Reverse Spain ne E EE N AEE ENESE E REE DANNE ENEE ESES 11 Channel Eet 12 Jegen rssi tnes pr eas e EE eee a 12 Error e 12 Modbus diagnostics P
10. different type are physically different registers However some devices are mapping the registers of different types and the same address to physically the same register See documentation of your device for details The Modbus convention for representing a resister type has the register type followed by the register number A Modbus slave device will have a manufacturer supplied mapping for each valid register type and register number The DT80 uses the following mapping for its registers when addressed as a slave device Modbus slave DT80 Channel register range 0001 to 1000 Channel variable 1 to 1000 4001 to 4053 System variables 1 to 53 8000 to 8009 Digitals 1 to 8 and 1Relay Table 1 DT80 range Modbus registers Page 4 of 16 TR 0011 A1 datalaker Training Note TR 0011 Putting this into standard Modbus convention we get Modbus register DT80 Channel DT80 action mapping Register type Comment Coil type is read write Coil 00001 to 01000 Channel variable 1 to 1000 Returns 0 or 1 If CV gt 0 then output 1 04001 to 04053 System variables 1 to 53 Returns 0 or 1 If SV gt 0 then output 1 08000 to 08009 Digitals 1 to 8 and 1Relay Returns digital state Register type Comment Discrete type is read only Discrete 10001 to 11000 Channel variable 1 to 1000 Returns 0 or 1 If CV gt 0 then output 1 14001 to 14053 System variables 1 to 53 Returns 0 or 1 If S
11. e word order of the slave device when reading 32 bit data A variation to Modbus known as ENRON Modbus is also supported by the DT80 range Modbus master implementation ENRON Modbus supports 32 bit data registers Planning a Modbus Task Because of the level of detail required for implementing a Modbus system it is strongly advised that the task is approached systematically Before you start e Understand the slave device capabilities o Communication method and set up RS232 o Assign unique device address o Understand Modbus register types o Understand Modbus register data types o Understand data word order e Understand the master device capabilities o Communication methods and set up o Slave device addressing o Howto read slave register types o Howto read slave register data types Page 6 of 16 TR 0011 A1 datalaker Training Note TR 0011 o How to address slave data word ordering e Design the system o Construct a Modbus register map that includes device numbers register types data types and details etc o Communications type to be used and settings o Other consideration Displays data handling etc e Implement and document o Program the system and deploy the system o Document the system components structure design details etc Don t forget to document the project Remember you might be the person who has to repair or modify the system at a future date Good documentation will greatly simplify the task DT80
12. empt to read only register Attempting to write data to a read only register E127 Modbus IP address specified on serial channel Attempting to use TCP IP address or domain name with a serial channel type e g 1Modbus AD 192 168 1 212 or 2Modbus AD My DT80 com Note For this addressing mode the serial channel will need to be configured for PPP communications E128 Modbus serial address specified on TCP IP channel Attempting to use Serial address with a Ethernet channel type e g 4Modbus AD192 Can also occur is serial channel is configured for PPP E129 Modbus unexpected format of response packet Returned data in not in Modbus format Most likely cause is device returning data is not Modbus device E130 Modbus unexpected function id in response Modbus slave returned incorrect function number E131 Modbus exception response received Error in response from Modbus slave device Probably due to slave device not supporting requested Modbus function E132 Modbus error in definition of CV block to send Error in defining channel variables to be written to registers e g 2MODBUS AD12 R4 1 100 10cv Page 12 of 16 TR 0011 A1 datalaker Training Note TR 0011 E133 Modbus reading values to CVs prevents writing Can not read and write to channel variables in the one transaction e g 2MODBUS AD12 R4 1 10CV 100CV E134 Modbus 32 bit format not applicable to discrete transfer Attempt to write a float
13. hannel Description 30001 3 holding reg Signed int 1CV Temperature 1 30002 3 holding reg Signed int 2CV Temperature 2 30003 3 holding reg Signed int 3CV Temperature 3 30004 3 holding reg Signed int 4CV Temperature 4 30005 3 holding reg Signed int 5CV Average Temp 04005 1 Discreet Digital 5SV Power On Off Comments Registers 1 to 5 have been multiplied by 10 All registers are read only Table 5 Modbus register map Chamber 1 Page 14 of 16 TR 0011 A1 datalaker Training Note TR 0011 Modbus Mapping Table Device details Name DT80 Serial Number 085533 Location Chamber B Communications Modbus TCP IP Modbus address 192 168 11 70 on Port 502 Modbus register details Modbus Register Register type Data type DT80 Channel Description 30001 3 holding reg Signed int 1CV Temperature 1 30002 3 holding reg Signed int 2CV Temperature 2 30003 3 holding reg Signed int 3CV Temperature 3 30004 3 holding reg Signed int 4CV Temperature 4 30005 3 holding reg Signed int 5CV Average Temp 04005 1 Discreet Digital 5SV Power On Off Comments Registers 1 to 5 have been multiplied by 10 All registers are read only Table 6 Modbus register map Chamber 2 Modbus Mapping Table Device details Name DT80 Serial Number 085533 Location Chamber C C
14. ing point number to a discrete input E135 Modbus volume of data to transfer exceeds Modbus message capacity Attempting to read or write to too many registers in one try e g 2MODBUS AD12 R3 1 1 500CV Note Maximum Modbus message length is 255 bytes Modbus diagnostics P56 4 Setting P56 4 will turn on the Modbus debug output When in this mode the Modbus communications between the master and slave devices will be returned Example This example is the conversation from a DT80 configured as a Modbus master and a Modbus slave device and show a successful Modbus transaction and a CRC failure 1CV 1 2CV 2 3CV 3 4CV 5 5CV 0 2MODBUS AD12 R4 1 1 5CV Modbus TX gt HOST Oc 04000000053114 8 Modbus RX lt HOST Oc 040a00010002000300040000e9al1 15 2MODBUS 5 2ZMODBUS AD12 R4 1 1 10CV Modbus TX gt HOST Oc 100000000a14000100020003000400050006000700080009000023d6 29 INVALID RX MSG calc CRC c130 Modbus CRC check failed Modbus RX lt HOST Oc 100000000a41 7 dataTaker 80 E124 Modbus transaction failed 2MODBUS 9e9 Data type range limiting When writing values to a Modbus slave device eg 4MODBUS 1CV if the value of the expression is outside the range of the target Modbus register then it will be set to the register s max min value For example the following command 2MODBUS ad12 MBI R4 1 483648 takes the value 483648 and tries to write it to a 16 bit signed integer As the maximum value a 16 bit signed in
15. n some Modbus client applications register numbers are entered using these raw protocol addresses while in others you specify register numbers including the initial register type digit as described above The documentation for the particular package should make clear which convention it uses The Modbus protocol then defines a set of messages which allow the client to e read the current value of one or more of the slave s coils discrete inputs input registers or output registers e write to one or more of the slave s coils or output registers A given type of Modbus slave device will support some quantity of each type of resource for example a hypothetical device might support 16 coils 16 discrete inputs 4 input registers and no output registers Furthermore it is common for the different register arrays to overlap In the example device mentioned above the 16 coils and discrete inputs may actually refer to the same physical hardware in this case 16 bi directional I O pins So for this slave device if a client wrote a 1 to coil 00007 it would then read the same value back if it did a read from discrete input 10007 Page 5 of 16 TR 0011 A1 datalaker Training Note TR 0011 Modbus data types The Modbus standard only defines the size of the registers as being 16 bit wide It does not detail how the data is to be stored in the registers While the Coil and Discrete register types are only 1 bit the representation of number
16. ommunications Modbus TCP IP Modbus address 192 168 11 71 on Port 502 Modbus register details Modbus Register Register type Data type DT80 Channel Description 30001 3 holding reg Signed int 1CV Temperature 1 30002 3 holding reg Signed int 2CV Temperature 2 30003 3 holding reg Signed int 3CV Temperature 3 30004 3 holding reg Signed int 4CV Temperature 4 30005 3 holding reg Signed int 5CV Average Temp 04005 1 Discreet Digital 5SV Power On Off Comments Registers 1 to 5 have been multiplied by 10 All registers are read only Table 7 Modbus register map Chamber 3 Inspecting the Modbus register maps for these devices it can be seen that the data is read only and we need to read 1 Holding Register 30005 for the average temperature 2 Discreet input register 04005 for power state 3 TCP IP address of each unit Page 15 of 16 TR 0011 A1 datalaker Training Note TR 0011 Implementation Profile settings In this case there are no profile settings required to configure the DT80 as a Modbus master device other than the network setting needed to establish TCP IP communications DT80 Code BEGIN MASTER RA10S 4MODBUS AD 192 168 11 69 R0 4005 CHAMBER A POWER AMODBUS AD 192 168 11 69 R3 5 MBI CHAMBER A AVE 176C 0 1 4MODBUS AD 192 168 11 70 R0 4005 CHAMBER B POWER AMODBUS AD 192 168 11 70 R3 5 MBI CHAMBER B AVE 176C 0 1 4MODBUS AD 192 168 11 71 R0 4005 CHA
17. ously connect to the DT80 using TCP IP The first step in setting up Modbus over TCP IP is to establish a working TCP IP connection between the client system and the DT80 This involves assigning an IP address to the DT80 along with a couple of other settings depending on whether Ethernet or PPP is used By default the DT80 s TCP IP Modbus server is always enabled It will listen for connection requests from client systems which are directed to TCP port 502 which is the standard port number for Modbus Slave addresses are not required on a TCP IP Modbus network because the slaves are identified by their IP address Modbus register types The Modbus message consists of e Address of the Modbus slave device o Inthe range of 1 to 247 for serial devices o TCP IP address for network devices e Register type o D Coil Digital Read and Write o 1 Discrete input Digital Input Read only o 3 Input register 16 bit input registers Read only o 4 Output register 16 bit output registers Read and Write e Register address o Either a 5 or 6 digit numbered address for the registers Device dependant o Inthe range of 1 to 65535 e The register number will depend on the device Most devices have more than one register and most register may be used in more that one type e The devices are likely to support only specific subset of available device range for one or more register types e In general case the registers of the same address and
18. re e xx the data type one of o l 16 bit signed integer default o U 16 bit unsigned integer o L 82 bit signed integer transferred using two consecutive 16 bit registers o F 82 bit float transferred using two consecutive 16 bit registers o LE 32 bit signed integer transferred using Enron Modbus protocol variant Example 1 1MODBUS AD12 MBI R3 1 Modbus read on the serial sensor port Slave address 12 Register type 3 Input register 1 as a signed integer Example 2 1MODBUS AD12 MBU R3 1 Modbus read on the serial sensor port Slave address 12 Register type 3 Input register 1 as a unsigned integer Word Order Endian MEx Where e x the word order one of o s straight endian most significant word first default o f reverse endian least significant word first Note The word order only applies to MBL or MBF data types Example 1 2MODBUS AD12 MBF MES R3 1 Modbus read on the Host port Slave address 12 Register type 3 Input register 1 as a 32 bit floating point number Transfer is largest word first then small word second Example 2 2MODBUS AD12 MBF MER R3 1 Modbus read on the Host port Slave address 12 Register type 3 Input register 1 as a 32 bit floating point number Transfer is mall word first then large word second Timeout TOn Where e n the timeout for Modbus master requests in seconds Note The value must be between 1 and 255 with the default being 3 Example 2MODBUS AD12 R3 2 TO10
19. s can vary depending on the type of number and the type of computer system being used Note Which ever method of representing data a system is using it is important that the Modbus master be configured to read the matching data format types from the slave device Data Type Range 16 bit signed integer 32768 to 32767 16 bit unsigned integer 0 to 65535 32 bit signed integer 2 147 483 648 to 2 147 483 647 32 bit floating point number 3 4028e38 to 3 4028 38 Table 3 Data types and approximate range To represent decimal numbers with integer data types the slave will take a reading and multiply the number by a scalar then place the scaled number in the register The master will then read the device register and divide the number by the same scalar For example a slave device may read a thermocouple temperature as 23 4 degrees C If it puts this value in a holding 16 bit signed integer the decimal place will be lost To overcome this limitation the slave multiples the temperature value by 10 so the register now hold the value 234 When the master reads this value it will divide the register value by 10 to restore the decimal place 32 bit data types are stored across two consecutive Modbus registers While the Modbus standard does state that data in a register is in High byte Low byte format Big endian it does not specify the word order endian when data is across registers For this reason you need to be aware of th
20. teger can hold is 32767 then the value 32767 is transmitted to the slave device Page 13 of 16 TR 0011 A1 datalaker Training Note TR 0011 Worked example Configuring the DT80 as a Modbus master Example A DT80 will be used to read data from the Modbus registers of other DT80 s that are being used to monitor the performance of 3 environmental chambers The DT80 Modbus master will read the registers for average temperature and power state from each of the three environmental chambers and log the data Modbus communications will be over a TCP IP network The DT80 s attached to the environmental chambers will read 4 PT100 RTD temperature sensors and display the temperature with one decimal place The average of the 4 temperature will also be displayed The average reading will be tested in an alarm for over or under range condition set point 1 Deg C The external power state will also be read from 5 SV Modbus communications will be via Ethernet Note 5SV System Variable holds 1 if mains power is connected 0 if disconnected Planning The first step is to gather the Modbus register maps and Modbus addresses for each device Modbus Mapping Table Device details Name DT80 Serial Number 085533 Location Chamber A Communications Modbus TCP IP Modbus address 192 168 11 69 on Port 502 Modbus register details Modbus Register Register type Data type DT80 C
21. ween loggers e Gateway device o SDI 12 to Modbus o RS232 RS422 RS485 to Modbus o Modbus to web server Limitations The DT80 range Modbus Master has the following limitations e Does not support Modbus ASCII e Does not support long 32 bit unsigned integer data type Modbus communications methods Modbus can operate using a broad range of communications media These fall into two main categories e Serial connection typically RS232 RS422 or RS485 e TCP IP network which can use a variety of physical link types e g Ethernet wireless fibre optic serial PPP The DT80 supports both TCP IP and serial Modbus networks Serial Connection A serial Modbus network has one master system connected to one or more slave devices Serial networks using the RS485 or RS422 standards support multi drop i e multiple slaves connected to one master RS232 can also be used for point to point connections single master and single slave Slave devices on a serial Modbus network are identified by an 8 bit slave address 1 247 Every slave device on a particular serial network must have a unique address The DT80 can be connected to a serial Modbus network using either the serial sensor port the host RS232 port or the USB port The serial sensor port on the DT80 can be configured for RS232 RS422 or RS485 modes Page 3 of 16 TR 0011 A1 datalaker Training Note TR 0011 TCP IP Connection Multiple Modbus Slave devices can simultane
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