Frequency Inverter DF51... - Moeller.com.tr

04/07 AWB8230-1541GB The network protocolFunction code Function Modbus standard name Maximum datasize (availablebytes permessage)Maximum numberof data elementsper messagedechex15 0F Write multiple bit variables (coils) Force multiple coil 4 32 coils (in bits)16 10 Write multiple word variables (register) Force multiple registers 4 4 registers (in bytes)Data elements: 1 byte = 8 bitsError checkModbus RTU uses cyclic block testing, also called CRC (cyclicredundancy checking) to check the data transfer for errors. TheCRC code is a 16-bit data word consisting of 8-bit data blocks ofany length. The CRC checksum is generated with generatedpolynomial CRC-16 (X16 + X15 + X2 + 1).Non-operational mode (header and trailer):The latency is the time between the request from the master andthe response from the frequency inverter (slave), i.e. the time inwhich the changeover between transmission and reception takesplace. At least 3.5 characters (24-bit rest time) of latency arealways required. If the time is shorter, is the frequency inverterdoes not respond. The actual latency is the sum of the rest time(3.5 characters) and PNU C078 (waiting time until fault message).Structure of responseRequired transfer time• The time between receiving a request from the master and thefrequency inverter’s response consists of the rest time (3.5characters) and PNU C078 (the waiting time to the faultmessage).• Once the master has received a response from the frequencyinverter, it must wait for at least the rest time before it can senda new request.Normal response• If the master’s request contains the loopback function (08 hex ),the frequency inverter returns the same content.• If the request contains a write register function (05 hex , 06 hex ,0F hex or 10 hex ), the frequency inverter returns the request as itsresponse.• If the request contains a read register function (01hex, hex or03 hex ), the frequency inverter returns the read data with theslave address and function code as its response.Response in fault conditionIf the request contains an error (except for a transmission error),the frequency inverter responds with an exception message anddoes not perform an action.The exception message can be evaluated in the user program. Itconsists of the sum of the enquiry’s function code and code 80 hex .Structure of exception message:• Address (slave)• Function code• Error code• CRC-16ExceptioncodehexDescription01 The function is not supported.02 The specified address does not exist or was not found.03 The data format is not supported or is wrong.21 The number of the holding registers is too large or thedata is outside the frequency inverter’s range.22 • The function for changing register contents can notbe used during frequency inverter operation.• The function sends an ENTER signal duringoperation.• The function writes to the register duringoperation.• The function writes to read-only register or coil.No responseIn the following cases, the frequency inverter ignores the requestand does not send a reply:• on receiving a broadcast request.• if the request contains a transmission error.• if the slave address in the request does not match the inverter’saddress.• if the time interval between the data blocks is less than 3.5characters.• if the data length is invalid.h The master must be programmed to repeat the requestif it does not receive a response within a specified time.Explanation of function codesRead coil status [01 hex ]:This function reads the status (On/Off) of the selected coils. Forexample: reading input signal terminals 1 to 6 of the DF51 withslave address 8. In this example, the inputs have the followingstates.DesignationFunctionDigital input [1] [2] [3] [4] [5] [6]Coil status ON ON ON OFF ON OFF149