Mitsubishi Electric CR800 Series Ethernet Function Instruction Manual page 104

3 Description of functions
3.5.7.3. Self Test (Loopback Test) (Command: 0619)
Perform a test to determine whether communication between external devices and Ethernet-equipped modules is normal.
By performing a loopback test, it is possible to confirm whether the connection with the external device is correct, and
whether data communication is functioning properly.
* Loopback tests can only be performed for Ethernet-equipped modules connected to external devices. Loopback tests
cannot be used for other station modules connected via a network.
 Request data
Binary code
Sub-
command
• Subcommand
• Loopback data quantity
Specify the "Loopback data" quantity in bytes. The range that can be specified is 1 to 960 bytes.
Example
When the loopback data quantity is 5 bytes
When using ASCII, convert the number of bytes to 4 ASCII code digits (hexadecimal), and send them in the order
from higher-order byte to lower-order byte.
When using binary code, send the number of 2-byte characters indicating the number of bytes in the order from
lower-order byte to higher-order byte.
• Loopback data
Specify the data sent and received when performing a loopback test.
When performing data communication in ASCII code, specify a 1-byte character string ("0" to "9", "A" to "F") for
data with maximum of 960 characters, and send from the start.
When performing data communication in binary code, convert the 1-byte character ("0" to "9", "A" to "F") code to a
1-byte numerical value, and send data with maximum of 960 bytes from the starting character code.
3-78
Loopback data
Subcommand
quantity
Loopback
Loopback data
data
quantity
ASCII code
Loopback data
Subcommand
Binary code