V230 time shifting problem

[gotnoname]

Hello

at our company the light’s of the building are controlled by a Unitronics V230,

there are 2 IO-DI16, 2 IO-RO16 and one IO RO8

we read the status of motion detectors with the inputs, and the outputs switch the lights on and off.

for central control we use a Proface screen that communicates via modbus ip

we have a problem, that the system time changes at night, it shifts a couple of hours back each night

we have temporarily removed all functions that can influence the time in the project .

we have disconnected the Proface screen for one night to see if the Proface was changing the time ,but the time was still shifted

the project is in written in visilogic 9.3

does anyone recognize this problem? and how can I find out what is influencing the time?