Figure 4.18 command frame, Figure 4.19 response frame ê, Test data – Rockwell Automation 900 Temperature Controller Communications Functions - Series B User Manual
Page 81: Response code, Example command and response, Echoback test -22, Echoback test
Publication 900-UM004D-EN-E - July 2010
Modbus Communications Procedure
4-23
Echoback Test
Figure 4.18 Command Frame
Figure 4.19 Response Frame ➊
➊ When the command is executed normally, the response returns the same data sent in the command.
Test Data
Enter any 2-byte hexadecimal data.
Response Code
Example Command and Response
The following example shows the command/response for an Echoback Test
command.
Table 4.18
Function Code
Error Code
Name
Description
H’88
H’03
Variable data
error
The data following the function
code was not the fixed data
(H’00, H’00).
H’08
—
Normal
completion
No errors were found.
Power ON
Software reset command
Setting area 0
Setting area 1
“Move-to-setting
area 1” command
Control in progress
Control stopped.
CRC-16
1
1
2
2
H'08
H'00
H'00
Test data
2 bytes
Slave
address
Function
code
Write
start address
CRC-16
1
1
2
2
H'08
H'00
H'00
Test data
2 bytes
Slave
address
Function
code
Write
start address