RS485 INTERFACE (MODBUS RTU)COMMUNICATIONS GUIDE

Table 8: Master/slave packet format for function code 10H

MASTER TRANSMISSION

BYTES

EXAMPLE

DESCRIPTION

 

 

 

 

SLAVE ADDRESS

1

11

message for slave

 

 

 

17

 

 

 

 

FUNCTION CODE

1

10

store setpoints

 

 

 

 

DATA STARTING ADDRESS

2

04 5C

setpoint address

 

 

 

04 5C

 

 

 

 

NUMBER OF SETPOINTS

2

00 02

2 setpoints = 4

 

 

 

bytes total

 

 

 

 

BYTE COUNT

1

04

4 bytes of data

 

 

 

 

DATA 1

2

00 02

data for setpoint

 

 

 

address 04 5C

 

 

 

 

DATA 2

2

01 F4

data for setpoint

 

 

 

address 04 5D

 

 

 

 

CRC

2

31 11

CRC error code

 

 

 

 

SLAVE RESPONSE

BYTES

EXAMPLE

DESCRIPTION

 

 

 

 

SLAVE ADDRESS

1

11

message from

 

 

 

slave 17

 

 

 

 

FUNCTION CODE

1

10

store setpoints

 

 

 

 

DATA STARTING ADDRESS

2

04 5C

setpoint address

 

 

 

04 5C

 

 

 

 

NUMBER OF SETPOINTS

2

00 02

2 setpoints

 

 

 

 

CRC

2

82 7A

CRC error code

 

 

 

 

Error Responses

When a MM300 detects an error other than a CRC error, a response will be sent to the master. The MSBit of the FUNCTION CODE byte will be set to 1 (i.e. the function code sent from the slave will be equal to the function code sent from the master plus 128). The following byte will be an exception code indicating the type of error that occurred.

Transmissions received from the master with CRC errors will be ignored by the MM300. The slave response to an error (other than CRC error) will be:

SLAVE ADDRESS: 1 byte

FUNCTION CODE: 1 byte (with MSbit set to 1)

EXCEPTION CODE: 1 byte

CRC: 2 bytes

The MM300 implements the following exception response codes:

01 - ILLEGAL FUNCTION

The function code transmitted is not one of the functions supported by the MM300.

02 - ILLEGAL DATA ADDRESS

The address referenced in the data field transmitted by the master is not an allowable address for the MM300.

03 - ILLEGAL DATA VALUE

The value referenced in the data field transmitted by the master is not within range for the selected data address.

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MM300 MOTOR MANAGEMENT SYSTEM – COMMUNICATIONS GUIDE

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GE MM300 manual Error Responses, Master/slave packet format for function code 10H

MM300 specifications

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In summary, the GE MM300 stands out due to its scalability, versatile communication options, high processing capabilities, user-friendly programming environment, rugged design, and security features. These characteristics make it a reliable choice for industries seeking to enhance their automation processes and improve overall efficiency. Whether for small-scale or large-scale applications, the MM300 provides a comprehensive solution to meet the evolving needs of modern manufacturing.