Dwyer UXF3 - Manual (Page 14)

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5.3 Response of Slave Station
(1) Response for normal command
To a relevant message, the slave station creates and sends back a response message which corresponds to the
command message. The composition of message in this case is the same as in Section 5.2.
Contents of the data field depend on the function code. For details, refer to Chapter 6.
(2) Response for abnormal command
If contents of a command message have an abnormality (for example, non-actual function code is designated)
other than transmission error, the slave station does not execute that command but creates and sends back a
response message at error detection.
The composition of response message at error detection is as shown in Fig. 5-2 The value used for function
code field is function code of command message plus 80
H
.
Table 5-1 gives error codes.
Station No.
Function code + 80
H
Error code
Error check 㧔CRC-16㧕
Fig. 5-2 Response message at error detection
Table 5-1 Error Code
Error code Contents Description
01H Illegal function code Non-actual function code is designated.
Check for the function code.
02H Illegal data address A relative address of a resister number to which the
designated function code can not be used.
03H Illegal data number Because the designation of number is too much,
the area where resister numbers do not exist is designated.
(3) No response
Under any of the following items, the slave station takes no action of the command message and sends back no
response.
ƒ A station number transmitted in the command message differs from the station number specified to the slave
station.
ƒ An error check code is not matched, or a transmission error (parity error, etc.) is detected.
ƒ The time interval between the composition data of the message becomes longer than the time
corresponding to 24 bits. (Refer to Section 5.6 Transmission Control Procedure)
ƒ Station No. of a slave station is set to 0.
ƒ Setting is made on the main unit with the operation keys.
ƒ The main unit displays a write-in command on a screen other than the measurement screen.
Bulletin F-107-UXF3-S