RV50x modbus message issues

Hello I have a simple setup with 2 RTUs communicating via modbus through the RV50x. They are setup as 9600baud and communicate once a minute. They were working fine but about 5 hours after I finished the setup they started to have cimmunication failure. Communication fail is 5 missed messages in a row. Any ideas? Perhaps there is a setting that I didn’t configure correctly. I noticed that the signal strength was green for both units but the one would sometimes switch to a different tower thas was yellow signal strength. Is there anyway to lock it into the better signal strength tower. Is it possible that 9600 baud is too low to accurately work? Looking for any help on this issue.

Hi Matt1,

How do you check that Communication fail is 5 missed messages in a row?
Do you use Wireshark to capture packages on the server or do you check the RV50 modem log for 5 hours?
What is the device connected to the RV50X?
Is the device connected to the RV50X a slave to listen to polls from the Master device?
Is the device connected to the RV50X data received on the serial port packaged into a TCP or UDP message and sent to the remote IP address and the Port specified in AceManager?

Could you please help to draw a topology with the various devices involved and their IP in the Modbus of your case so I can figure it out?

No, it isn’t. It depends on the network signal. You can attach the antenna to the gateway for better signal strength.

Let me go into more detail. We have a sneider electric scadapack PLC comunicating via serial rs232 once a minute to the RV50x using modbus rtu in tcp port 1234 (i picked this randomly). The other end is the same, sneider electric scadapack connected serial to RV50x. Probably 80% of the time it works but it’s the %20 that it doesn’t that I’m concerned about. The message instruction in the scadapack gives a successful or failure bit after the instruction resolves. The failure bits are what I’m using to see that the message failed. There is no indication of a failed message in the log. It does say that modbus table not found address 10, this is in the remote rv50. I don’t understand that message because the table is setup in the master rv50 and it works most of the time. The only thing I noticed is that the SINR seems to get very low (0-3) during a failed message. I wonder if we are getting interference? Also we are not using diversity antenna and I wonder if that might solve the problem if interference is the issue here. I’m looking for anything to test out as I can remotely management turned on the modems. Thanks

Hi Matt1,

SINR value does not depend on diversity antenna. The values vary depending on the network characteristics and the AirLink RV50, but in general, a positive value provides usable throughput. The following table provides guidelines for interpreting SINR values.

If the SINR value indicates poor throughput:
• Move the antenna away from noisy equipment.
• Move closer to the nearest cell tower line of sight, or further away from the interfering cell tower.

Please refer to page 504 in ALEOS Software configuration User Guide.

The antenna gain must not exceed the limits and configurations shown in the following table:

Please refer to page 62 in AirLink RV Series Hardware User Guide

Hello Matt1

Do the SCADApacks talk to each other or to ClearSCADA? We have over 50 SCADAPacks 357’s Some 32’s that we use RV50 to communicate to ClearSCADA and we do not have any issues with them logging data every minute. Just wondering.

The scadapacks are talking to each other through the serial port rs-232 using the master communication block. Like I said most of the time it works but there are random gaps of time where the messages are not successful. I am wondering if the low sinr is caused by interference. If it is I’m not sure what I can do about it. I can move the antenna a little bit but random interference doesn’t seem like it would be stopped by a slight location change to me and from what Donald said adding a diversity antenna wouldn’t help either. I’m just not sure what I need to do.

One other thing is this message is in the log every minute(same as we are polling data) Feb 22 01:13:19 err ALEOS_SERIAL_HMC: Modbus list NOT found matched ID 10.

The modbus address of the plc connected to the modem is 10. The thing is it works most of the time so I didn’t think this error was a problem but I thought I better say something.

I decided to attach the master and remote logs in case you all spot something odd in them.

master log 2-26-20.txt (1.1 MB) remote log 2-26-20.txt (1.0 MB)