504 to pv 300 micro

Driving me Crazy (I could not find an answer through the search feature)
SLC 504 to Panel view 300 Micro (error 686 offline)
I have SLC 504 1747-L542 ser B with a Panel view Micro 2711-M3A18L1 SER A using a 2711-CBL-PM10 Cable (not talking anymore) through RS232 PORT. This all seemed to work before and nothing has changed. But past couple of times using the machine we had to cycle the power multiple times to get communication between the 2 devices. On the panel view 300 micro we receive (Error 686 offline).Also I cannot get online with the 504.I have been online with this one before, there are no faults showing. I can go online with other processors but they are not 504’s they are 503’s.
In the 504 I have the following settings
General tab
Channel 1=DH+ Channel 0= system driver = DF1 Full duplex User Driver = ASCII
Channel 1 system= DH+ DRIVER 57.6 K BAUD NODE 1
Channel 0 system Driver=DF1 Full duplex Baud 9600 Parity=none No handshaking and CRC Detection
Channel 0 user= Driver ASCII Baud= 1200 Parity =none Protocol= no handshaking
300 Micro
DF1 Full duplex
F1 Comms= N/8/1
Baud=9600
Error=CRC
Hand =off
Node=2
Question should the baud rates be the same in the Channel 0 user baud and the micro baud.
And if the settings look ok what would cause this? The cable looks fine no obvious signs of damage.
All help is appreciated
Thanks

The "User" mode configuration doesn't have to match the "System" mode configuration.

Unless somebody has switched the SLC into User Mode, you were using System mode and DF1 Full Duplex to communicate with the PanelView. The fact that it works "sometimes" suggests that the configuration wasn't changed.

If the PanelView communications has failed, and you can't get even a browse from RSLinx on the SLC serial port, I suspect you have a failed serial port. It's uncommon, but it can happen.

Now the darn thing is working and I did nothing but call it a bad name.Processor maybe?
Thanks Ken

I did connect to another 504 to make sure my cables and laptop were OK and auto config worked.Connected right away.So it does seem like the serial port is a little flaky.
Thanks for the help

There could be a loose pin, or a damaged transceiver, or something else just waiting to fail in accordance with Murphy's Law.

The fact that you can't go online with the SLC-5/04 during these periodic failures suggests that the problem is in the controller, not in the cable or in the PanelView terminal.

Whether you replace the controller as a preventative measure depends on how critical the process is.

Upgrading to a 505 was something I was thinking about to get Ethernet capabilities,and or trying to put in a Cmore HMI To gather data so i can send a email to myself when production has stopped for more then 5 min.

Thanks for the help.

Just an update.I replaced the controller with another SLC 504 and it communicated right away with the panel view 300 micro .So it seems the RS 232 Port was bad on the SLC 504.
Thanks for the suggestions