Schneider Electric VW3 A3 303 user manual Exception responses, Response, Code Error code

Page 37

8. Modbus protocol

8. 12. Exception responses

An exception response is returned by a slave when it is unable to perform the request which is addressed to it.

Format of an exception response:

Slave	Response			Error		CRC16
no.		code		code	Lo		Hi
no.		code		code


1 byte	1 byte			1 byte		2 bytes
Response	request code + H’80.
code:
Error code:	1 =		The function requested is not recognized by the slave.
	2	=	The addresses indicated in the request do not exist in the slave.
	3	=	The values indicated in the request are not permitted on the slave.
	4	=	The slave has started to execute the request but cannot continue to process it completely.
	6	=	The requested write operation has been refused because the drive is in "Forced local" mode.
	7	=	The requested write operation has been refused because the motor is running (configuration parameters).

Example: Writing the value 1 to the status word (EtA) = logic address 3201 (which cannot be written, because in “read-only" mode) on slave 4

Request:

Slave no.

Request

No. of 1st word

No. of words

No. of

Value of 1st word

CRC

CRC

code

Hi

Lo

Hi

Lo

bytes

Hi

Lo

Lo

Hi

4

10

0C

81

00

01

02

00

01

8A

D1

Response:

Slave no.

4

Response

code

90

Error code

00

CRC

Lo

5C

CRC

Hi 01

37

Image 37

Contents Altivar Contents Electric shock will result in death or serious injury Before you beginDocumentation structure Installation ManualProgramming Manual Communication Parameters ManualPresentation IntroductionNotation Installing the card in the drive Hardware setupReceipt Hardware descriptionChoosing polarization Switch codingCoding the address 1234 AddressWiring recommendations Connecting to the busModbus RS485 standard Connection accessories Connection via RJ45 wiring systemConnection cables Type of master Master interface Description Catalog number Connection cables for the masterTWD XCA RJ030 TSX SCP CMDescription Catalog Number Subscriber socket Connection via junction boxesRS485 double shielded twisted pair CablesTSX P ACC TSX CSA500Communication parameters ConfigurationControl via Modbus in I/O profile Control CommandControl via Modbus or the terminals in I/O profile Parameter Value CommentControl via Modbus or the terminals in Drivecom profile Control via Modbus in Drivecom profileConfiguration Communication scanner Example of configuration via the graphic display terminalRDY NET COM. Scanner InputCOM. Fault Management Communication faultsMonitored parameters CONFIG. COMM. MAPFormat Format Range Terminal displayChecking the address DiagnosticsLEDs Green RUN Red ERR Meaning Corrective actionCommunication MAP RUN NETCOM. Scanner Input MAP COM Scan Output MAP CMD. Word ImageOutput variable Scanner parameter Input variable Scanner parameterCOM Scan Output MAP Card fault Communication faultPrinciple Modbus protocolSlave Slave j Slave k Ascii mode RTU modeModes Slave address Function code DataRead Holding/Input Registers 3/4 Modbus functions availableCode Modbus name Description Broadcast Size of data Write Single Register Diagnostics Write Multiple Registers 16 = 16#10 Get Comm Event Counter 11 = 16#0BRead/Write Multiple Registers 23 = 16#17 Machine Read Device Identification 43 = 16#2BMEI Example of positive responseInput variables Logic address Default assignment Output variables Logic address Default assignmentCode Modbus name Description Size of data Parameter Logic Read Input variable address Logic address Default valueParameter Logic Parameter assigned Output controlInput monitoring Value Parameter assignedException responses Code Error codeResponse Logic address Parameter Value Read non-existent or protected parametersRS485 standard AppendixMaster Modbus 2-wire standard schematicModbus 4-wire standard schematic Uni-Telway schematic Type of trunk cable Cable with 1 shielded twisted pair Wire Jbus schematicDifferent scenarios Creating a Modbus bus using non-standard equipmentRecommendations Example Calculating the polarizationCard connector pinout RS485 schematic for the cardContact no. Signal SUB-DAtv71ModbusJbusENV1 2005-05