Siemens S7-1200 - Unable to get Remote PLC data

Hi All,

We have 3 Remote Station (Buoy), 1 Control Room (STU) and 1 Portable unit (Tablet) at site. This is a Telemetry unit, and the data are transmitted with VHF Radio. Each Remote Station, there are 2 PLC's named Main PLC#1 and Partner PLC#2. At STU, there is one PLC and HMI (IP: 192.168.0.101). The Siemens S7-1200, Part: 6ES7212-1HE40-0XB0. The PLC configuration established with MBServer and MBClient. Attached the PLC IP address, Port and Slave ID of Individual PLC's.

The problem is, Buoy #2 and Buoy #3 has reliable connection. But, Buoy #4 does not have reliable connection. The Buoy #2 & Buoy #3 data updates regularly. But Buoy #4 data updates once in 1 hour.

We tested below point,

1. When STU PLC is not connected - Using MODSCAN64, we able to get all 3 remote stations data and able to ping using command prompt at STU.

2. When STU PLC is connected, we able to get Buoy #2 & Buoy #3 data and ping both with Error Code: 16#0000, 16#7002. And, unable to get Buoy #4 data as well unable to ping it with Error Code: 16#80c5, 16#80c6 and 80c8 comes rarely.

3. Also, we disabled the Buoy #2 and Buoy #3 MBServer and MBClient Configuration at STU program and enabled only the Buoy #4 MBServer and MBClient Configuration to check the Buoy #4 data. But the result is same. Unable to ping and get the data of Buoy #4.

What will be the solution? Please Check the attachment and correct if I am wrong.