Using the D2–DCM with MODBUS
Contents
1. 100 V2100 1088 decimal te ene Memon ir thig able 1088 Hold Reg Holding Reg 1089 2 Convert V2100 into decimal 1089 3 Use the MODBUS data type from the table Timer Current Values V4 YO W177 0 127 XI Input Register Counter Current Values 4 i000 1177 512 639 Input Register Y Memory user data 1024 2000 3777 1024 2047 Holding Register gt Find the MODBUS address for output Y20 PLC Addr Dec Start Addr Data Type 1 Find Y outputs in the table Y20 16 decimal 2 Convert Y20 into decimal 16 16 2049 Coil 3 Add the starting address for the range 2049 4 Use the MODBUS data type from the table omen a ax Control Relays CR 256 c C3 3072 Find the MODBUS address to obtain the PLC Address Dec Data Type current value from Timer T10 TA10 8 decimal 1 Find Timer Current Values in the table 8 Input Reg Input Reg 8 2 Convert T10 into decimal 8 3 Use the MODBUS data type from the table Timer Current Values Vv WO 177 0 127 Cinput Register Counter Current Values Vv v1000 1177 512 639 Find the MODBUS address for Control Relay PLC Addr Dec Start Addr Data Type Con C54 44 decimal 1 Find Control Relays in the table 44 3073 Coil Coil 3117 2 Convert C54 into decimal 44 4 3 Add the starting address for the range 3072 4 Use the MODBUS data type from the table N E E A C2. BUS Address There are typically two ways that most host software packages allow you to specify a PLC memory location These are e By specifying the MODBUS data type and address e By specifying a MODBUS address only If the Host Software Many host software packages allow you to specify the MODBUS data type and the MODBUS Requires the Data address that corresponds to the PLC memory location This is the easiest method but not all Type and Address packages allow you to do it this way The various MODBUS data types were presented earlier but they have been included again in the following table The actual equation used to calculate the address depends on the type of PLC data you are using The PLC memory types are split into two categories for this purpose e Discrete X SP Y CR S T contacts C contacts e Word V Timer current value Counter current value In either case you basically convert the PLC octal address to decimal and add the appropriate MODBUS address if required The following tables show the exact equation used for each group of data Dec Octal Address Range Data Type For Discrete Data Types Convert PLC Addr to Dec Start of Range Data Type Inputs X XO X477 2048 2367 Input Special Relays SP SPO SP137 3072 3167 Input SP540 SP617 3280 3471 Timer Contacts T Coil For Word Data Types Convert PLC Addr to Dec Data Type Counter Gurent Values V gt V Memor
3. Using the D2 DCM with MODBUS Data Communications Module 2nd Edition 2 03 C 2 Using the D2 DCM with MODBUS Introduction How Does the D2 DCM work with MODBUS The D2 DCM can be used as a slave interface to a network using the MODBUS RTU protocol To use the D2 DCM with MODBUS your host software must send a MODBUS function code and a MODBUS address to specify a PLC memory location that is understood by the D2 DCM Host sends a MODBUS request n nA a What s the status of Y0 EEE cca lt gt _ y o D2 DCM D2 DCM responds responds Y0 is ON with data It would be quite difficult to discuss all of the ins and outs of MODBUS in this document Instead the purpose of this Appendix is to e provide a quick overview of MODBUS Data Types and Function Codes e how to determine the proper MODBUS address necessary to allow the host software to access various memory locations in the DL205 system One key point to remember is that not all host software packages using MODBUS drivers operate exactly the same way That is there are a couple of different ways to achieve the same result especially when it comes to specifying the needed address for the PLC memory location Therefore it is important that you follow the instructions for your particular software package or network master Data Communications Module 2nd Edition 2 03 C 3 Using the D2 DCM with MODBUS MODBUS Functio
4. ficant position of the K4128 word will cause the RX to use function 04 30001 range LDA 04000 RX YO 1 Refer to your PLC user manual for the correct memory mapping size of your PLC Some of the addresses shown above might not pertain to your particular CPU 2 For an automated MODBUS Koyo address conversion utility download the file modbus_conversion xls from the www automationdirect com website Data Communications Module 2nd Edition 2 03 C 9 Using the D2 DCM with MODBUS Example 1 V2100 Find the MODBUS address for User V PLC Address Dec Mode Address 584 984 Mode acato V2100 2100 1088 decimal 1 Find V memory in the table 1088 40001 41089 2 Convert V2100 into decimal 1088 3 Add the MODBUS starting address for the mode 40001 For Word Data Types PLC Address Dec Appropriate hlode Address Timer Current Values Vv YO W177 0 127 3001 30001 Input Reg Counter Current Values V 128 1000 W117 512 639 3001 30001 Input Reg v Memory user data V 1024 V 2000 3777 1024 2047 4001 40001 Hold Reg Example 2 Y20 Find the MODBUS address for output Y20 PLC Addr Dec Start Address Mode 584 984 Mode 1 Find Y outputs in the table Y20 16 decimal 2 Convert Y20 into decimal 16 16 2048 1 3 Add the starting address for the range 2048 4 Add the MODBUS address for the mode 1 Oms se vo var fans yaar G fear Example 3 T10 Find
5. n The host software package reads or writes information by sending a MODBUS function code Codes Supported to the D2 DCM The following table provides a description of the MODBUS function codes supported by the D2 DCM MODBUS Code DL205 Data Types Available 03 04 Read a value from one or V more registers Write a value into a single V register 1 Write a value into a group V of registers NOTE The maximum MODBUS secondary address supported by the D2 DCM is 60 5A hex MODBUS Data Types You are probably accustomed to seeing data types like X input Y output C control relay V Supported memory data registers etc for the various types of memory in a DL205 system For example if you need to know the status of Y12 then you ask for Y12 MODBUS does not use these same data types so you have to determine which MODBUS data type corresponds to the PLC memory location that you need The following table will help DL205 Memory Type Quantity PLC Range Corresponding Decimal Octal MODBUS Data Type 320 SP540 SP617 56 06 Counter Current Value V V1000 V1177 Input Register V Memory user data V 1024 V2000 V3777 Holding Register V Memory user data V 2 V4000 V4377 Holding Register Non volatile V Memory system V 1 V7620 V7737 Holding Register V7746 7777 Data Communications Module 2nd Edition 2 03 C 4 Using the D2 DCM with MODBUS Determining the MOD
6. ng address as required The following tables show the exact range used for each group of data Discrete Data Types Memory Type PLC Range Address Address Octal 484 Mode 584 984 Mode Data Type Global Inputs GX GX0 GX1746 1001 1999 10001 10999 GX1747 GX3777 11000 12048 Inputs X X0 X1777 Lo 12049 13072 Special Relays SP SP0 SP777 Ss 13073 13584 Global Outputs GY Outputs Y Stage Status Bits S S0 S1777 Data Communications Module 2nd Edition 2 03 C 8 Using the D2 DCM with MODBUS Word Data Types Registers PLC Range Input Holding Input Holding Octal 484 Mode 584 984 Mode V Memory Timers VO V377 3001 4001 30001 40001 V Memory Counters V1000 V1177 3513 4513 30513 40513 V Memory Data Words V1200 V1377 3641 4641 30641 40641 V1400 V1746 3769 4769 30769 40769 V1747 V1777 a 31000 41000 V2000 V7377 en 41025 V10000 V17777 e 44097 MODBUS Function 04 New Feature The DLO5 06 DL250 1 260 DL350 and DL450 will support function 04 read input register Address 30001 To use function 04 put the number 4 into the most significant position 4xxx Four digits must be entered for the instruction to work properly with this mode LD The Maximum constant possible is 4128 This K101 is due to the 128 maximum number of Bytes that the RX WX instruction can allow The LD Ser value of 4 in the most signi
7. ontrol Relays CR co 0377 Q973 3551 Cail Data Communications Module 2nd Edition 2 03 C 7 Using the D2 DCM with MODBUS If the Host Software Some host software packages do not allow you to specify the MODBUS data type and Requires an Address address Instead you specify an address only This method requires another step to ONLY determine the address but it is not difficult Basically MODBUS also separates the data types by address ranges as well This means an address alone can actually describe the type of data and location This is often referred to as adding the offset One important thing to remember here is that two different addressing modes may be available in your host software package These are e 484 Mode 584 984 Mode We recommend that you use the 584 984 addressing mode if the host software allows you to choose This is because the 584 984 mode allows access to a higher number of memory locations within each data type If your software only supports 484 mode then there may be some PLC memory locations that will be unavailable The actual equation used to calculate the address depends on the type of PLC data you are using The PLC memory types are split into two categories for this purpose e Discrete X GX SP Y CR S T C contacts e Word V Timer current value Counter current value In either case you basically convert the PLC octal address to decimal and add the appropriate MODBUS starti
8. the MODBUS address to obtain the PLC Address Dec Mode Address Current Value current value from Timer T10 TA10 8 decimal 484 Mode i i l z 1 Find Timer Current Values in the table 8 3001 3009 2 Convert T10 into decimal 8 3 Add the MODBUS starting address for the mode 3001 For Word Data Types PLC Address Dec Appropriate hlode Address Tener Current Vaes 128 WO vivr o ver GoD 20007 wt Fay Counter Current Values V 128 1000 W117 512 639 3001 30001 Input Reg v Memory user data V 1024 2000 Y37 1024 2047 4001 40001 Hold Reg Example 4 C54 Find the MODBUS address for Control Relay PLC Addr Dec Start Address Mode 584 984 Mode C54 C54 44 decimal 1 Find Control Relays in the table 44 3072 1 3117 2 Convert C54 into decimal 44 3 Add the starting address for the range 3072 4 Add the MODBUS address for the mode 1 ouput 7 a Data Communications Module 2nd Edition 2 03
9. y user data V 256 V4000 V4377 2048 2303 Holding Register non volatile V Memory system V 106 V7620 V7737 3984 4063 Holding Register V7746 V7777 4070 4095 Counter Contacts CT S Stage Status Bits Data Communications Module 2nd Edition 2 03 C 5 Using the D2 DCM with MODBUS DL250 1 Memory Type QTY PLC Range MODBUS MODBUS Dec Octal Address Range Data Type For Discrete Data Types Convert PLC Addr to Dec Start of Range Data Type puis Special Relays SP SPO SP137 3072 3167 SP320 SP717 3280 3535 Contrai Relays CA co c77 256 Counter Contacts CT CTO CT177 6400 6527 Coil Stage Status Bits S 1024 S S1777 5120 6143 Coil For Word Data Types Convert PLC Addr to Dec Data Type Timer Current Values V VO V377 0 255 Input Register Counter Current Values V 128 V1000 V1177 512 639 Input Register V Memory user data V 3072 V1400 V7377 768 3839 Holding Register 4096 V10000 V17777 4096 8192 V Memory system V 320 V700 V777 448 768 Holding Register V7400 V7777 3840 3735 0 Timer Contacts T 256 TO T377 6144 6399 Coil 0 Data Communications Module 2nd Edition 2 03 C 6 Using the D2 DCM with MODBUS Example 1 V2100 Example 2 Y20 Example 3 T10 Current Value Example 4 C54 Find the MODBUS address for User V PLC Address Dec Data Type location e
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