Schneider Electric VW3A3310d Modbus TCP server, Modbus TCP frames, Drive Modbus servers

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11. Modbus TCP server

11. 1. Modbus TCP frames

Modbus TCP frames consist of a header and a Modbus request.

Header format:

	Byte	Description		Comments
	0	Transaction identifier	high order
	1	Transaction identifier	low order
	1		low order
	2	Protocol identifier	high order	This identifier always equals 0.
	3	Protocol identifier	low order	This identifier always equals 0.
	3		low order
	4	Length of data	high order	Number of bytes in the Modbus request +1. The frame length is always less than
	5	Length of data	low order	256 bytes, the value of the significant byte therefore equals 0.
	5		low order
	6	Destination identifier (Unit ID)
	7	Modbus request function code

The frame header returned by the Altivar 71 server is identical to that of the frame sent by the client.

11. 2. Drive Modbus servers

The destination identifier (Unit ID) is used to access 4 drive Modbus TCP servers:

Unit ID	Modbus TCP server	Accessible parameters
0	Variable speed drive	See the Altivar 71 Communication parameters Manual.
251, AMOC	Ethernet card	See the “Ethernet card parameters” section.
252, AMOA	Controller Inside card	2048 words (%MW0 to %MW2047).
255	IO Scanner	See the “IO Scanner” section.

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Contents Altivar 61 Page Table of contents Table of contents Please Note Important InformationHazard of Electric SHOCK, EXPLOSION, or ARC Flash Before you beginATV61 Installation ManualDocumentation structure Programming ManualPresentation IntroductionNotation Hardware description Hardware setupInstalling the card in the drive ReceiptExample of connection to an Ethernet network Connecting to the Ethernet networkCard RJ45 connector pinout Pin SignalEthernet network connection elements ENT Access to Ethernet menu via graphic display terminalAccess to Ethernet menu via the integrated display terminal Ethernet menuEthernet menu parameters IPF Code Description IPPIPP1 0.0.0 0 0 0 IPP2 IPP3 IPP4FdrE FdrAFdrS FdrtList of functions to be configured ConfigurationStatic Addressing Dynamic Configuring IP addressesPower-up Initialization Assigning IP addressesIP card IPC1 IPC2 IPC3 IPC4 IP Mask IPM1 IPM2 IPM3 IPM4 Configuring BootpConfiguring FDR Entering IP addresses in the terminalReserving control Configuring IO ScanningParameter Value Comment Configuring the controlControl via Ethernet in I/O profile Control via Ethernet or the terminals in I/O profileControl via Ethernet or the terminals in CiA402 profile Control via Ethernet in CiA402 Drivecom profileProfile Separate Communication Configuring communication interruption managementCommunication monitoring Network managementRDY NET COM. Fault ManagementExternal Fault Drive responseFormat Range Terminal display Configuring monitored parametersSignalling LEDs DiagnosticsColor/ state Description Terminal Workshop Web server Available informationMonitoring the control Integrated display Code Troubleshooting communication interruptions Ethernet communication interruption type Extended communication interruptionTroubleshooting the card TCP connections Software setupList of services supported Client Service Number of connectionsDrive Modbus servers Unit ID Modbus TCP server Accessible parametersModbus TCP server Modbus TCP framesIPM1.IPM2.IPM3.IPM4 Address Size Description Access Possible values, commentsEthernet card parameters IPC1.IPC2.IPC3.IPC4IPF1.IPF2.IPF3.IPF4 IPP1.IPP2.IPP3.IPP4FDR autosave Byte Meaning List of Modbus functions supportedRead Holding Registers 3 function Code Modbus name Description Size of data DecimalWrite Single Register 6 function Write Multiple Registers 16 = 16#10 function 16#17 Read/Write Multiple Registers 23 = 16#17 functionBytes Meaning With the VW3A3310d Ethernet card Read Device Identification 43 = 16#2B functionPeriodic variables IO Scanning serviceAddress table Address Description Default valueFDR service Local configuration IP assignment Save Downloading Downloaded configurationDrive parameters configuration First useCheck that the system is operational Save the drive configuration parameters in the FDR serverReplacing a drive Download the IP addressesLimitations Other commandsConfiguration file Periodic savingWeb server functions Home menu Monitoring menu Diagnostics menuSetup menu Security submenu Documentation menu Standard web serverApplets Username and password Access to the web serverHome menu Web server user interfaceMonitoring menu Altivar Viewer Data Viewer Diagnostics menu Altivar ChartEthernet Statistics Setup menuHttp password and Data write password pages Lcfg = No nO FDR AgentRestore Counter Local ConfigFile Error Error CodeIO Scanner Assigning the IO Scanning periodic variables Enabling IO ScanningMaster Time outImportant Notice MailDocumentation menu FTP server AccessDIR FunctionsFile system FTP functionality CommentFile name 32 characters max Downloading from the web serverPrinciple File managementWeb server Complete URL Bytes Standard web server resourcesType File name Size Complete URL Bytes Type File namePresentation Snmp agentTree structure Objects handled Objects Description Access Default valueATV Defining the hardware configuration Setup using PL7Bootp configuration Modbus Configuring Modbus messagingMulti Configuring periodic variables PLC Configuring the Dhcp address server FDR Setup using Concept Hardware configuration Traffic Cop Network configuration Setup using ProWORX NxTTCP/IP configuration O Scanner configuration Page 30072-452-37 2008-02