Loopback Test; Loopback Test (Command: Tt) - Mitsubishi Electric MELSEC IQ-R series Reference Manual

17.7

Loopback Test

17
A loopback test checks whether the communication function between an external device and C24 operates normally.

Loopback test (Command: TT)

Return the characters received from an external device to the external device unchanged.
Message format
The following shows the message format of the request data and response data of the command.
■Request data
Character Loopback
T T
Message wait
length data
54 54
H H
■Response data
Character Loopback
length data
Data specified by request data
■Command
ACPU common
T T
54 54
H H
■Message wait
Specify the delayed time of the response transmission. (Page 347 Message wait)
■Character length
Convert the numerical value to 2-digit ASCII code (hexadecimal), and send it from the upper digits.
Specify the character length within the following range:
• 1  Character length  254
■Loopback data
Store the loopback data for character length.
Data stored by response data
■Character length
The same data as request data is stored.
■Loopback data
The same data as request data is stored.
Specify 'FF' for PC No.
17 COMMUNICATING USING 1C FRAMES
389
17.7 Loopback Test