Rockwell-automation 900 Temperature Controller Communications Function Manuale Utente Scaricare il pdf (Pagina 81)

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

11 2 2

H'08 H'00 H'00

Te st data

2 bytes

Slave

address

Function

code

Write

start address