Step7 - Modify Value and Force Value

I have interface test between Quantum PLC and Siemens PLC.
When I change the output value in Step7 by "modify value", Quantum PLC receive the signal, but does not maintain the steady value.
Even though the modified value in step 7 maintains the steady value, the value in Quantum become zero and restore "modified value".

I think that Quantum PLC may reset the value once and restore.
If I give "Force value" in step 7, does Quantum PLC maintains the modified value ?

How have you setup the exchange of IO between the two controllers ?

I used gateways between S7 PLC and Quantum PLC.
For the first time, I used "modify value" in S7 PLC.
The modify value does not change in S7 and gateway. But, modify value in Quantum PLC change from value to 0, from 0 to modify value, by keep changing.

Today, I used "force value" in step 7. The situation is same.
Finally, I found that the Quantum PLC have two communication setting.
When "Clear Timeout" is set, the last value is set to 0.
When "Hold Timeout" is set, the last value stay.