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10.5 dead time

If the Nexus slave is in a 3.5 byte transmit time (about 7ms at 4800 baud rate; 115200 baud rate

is about 300us), it is considered that the data acceptance is completed. If the delay between the

two bytes of the master is greater than this time, the slave considers it dead time. the conclusion

from the dead time is that all unaddressed slaves must pay attention to new packets from the master.

10.6 Response of Exception Procedure

If the slave encounters an illegal command or other problem while executing the master command,

it will send an exception response packet to the master. The exception response packet contains an

error code to indicate the type of error.

The following table shows the error codes and the corresponding error types.

Table 1-5 Error Codes and Types

Error code error type

Interpret

01

illegal

The slave does not support the function number in the request packet

function

number

02

illegal

The slave does not recognize the address of the data area in the

address

transmitted request packet

03

illegal data The data mentioned in the transfer request packet is not supported

by registers in the Nexus slave

06

Busy, reject The slave is busy performing a long operation and cannot receive

package

the request packet

In the following example, the master device requests the value in register 00256 from the slave

with address 01H, and the slave sends an error response message indicating that it is busy.

Table 1.6 Exception Response Example

Host Package Meaning

hexadecimal

Slave Package Meaning

hexadecimal

address

address

Addr

01H

Addr

01H

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