3  TROUBLESHOOTING
3.4  Troubleshooting by Symptom
299
3
Communications using the predefined protocol cannot be performed.
When communications using the predefined protocol cannot be performed, check the following items and take action.
If the above action does not solve the problem, perform the module communication test to check for hardware failure. ( 
Page 284 Module communication test)
*3
*1 The buffer memory address is for when the network type of the RJ71EN71 or the RnENCPU (network part) is set to "Ethernet" and the 
P1 connector is used.
When using the P2 connector or the CPU module (built-in Ethernet port part), or setting the network type to "Q Compatible Ethernet", 
refer to the following.
Page 336 Buffer Memory
*2 If the connection of only the external device is closed due to cable disconnection, personal computer restart, or other reasons, reopen 
the connection using the same port used before the error occurred. The E71 does not close a connection if it receives an Active open 
request again from the external device with a different IP address or a port number.
*3 The module communication test cannot be performed for the CPU module (built-in Ethernet port part). Perform the troubleshooting of 
the CPU module and check for hardware failure. ( MELSEC iQ-R CPU Module User's Manual (Startup))
Check item Action
Is the IP address setting of the external device correct? Check and correct the IP address of the external device.
Has the connection with the external device been opened? (Check 'Open 
completion signal' (Un\G1900000 to Un\G1900007)
*1*2
• If the connection with the external device is not opened, perform the open 
processing.
• If an error occurs, check and eliminate the error cause.
Has the send/receive processing (dedicated instruction) for the 
communications using the predefined protocol been executed properly?
• If the send/receive processing has not been executed, check and correct 
the execution condition of the send/receive processing.
• If send/receive processing has completed with an error, check the error 
code in the completion status and eliminate the error cause.
Is the appropriate protocol used for the external device in the predefined 
protocol settings and program?
Correct the predefined protocol settings and program If inappropriate protocol 
is used.
For appropriate protocol for the external device, refer to the manual for the 
device used.
Is the communication method of the connection used for communication with 
the external device is set to an item other than "Predefined Protocol" in the 
"External Device Configuration" window of "Basic Settings"?
Correct the communication method setting if an item other than "Predefined 
Protocol" is set. ( Page 244 External Device Configuration)
Is 'Predefined protocol ready' (Un\G1901002.0) on?
*1
If 'Predefined protocol ready' (Un\G1901002.0) is off, write the protocol setting 
data to the module.