How can multiple SCADA hosts access the same
Modbus RTU devices at the same time with one gateway?
While the Moxa MGate can handle this, remember that the serial port bandwidth remains the same. If multiple requests arrive on the same serial port, there may be a delay as the gateway processes the earlier requests first. Therefore, if you want to allow multiple masters to access a Modbus RTU device at the same time, you first need to find a suitable polling time.
However, the solution described above is not the only one. The MGate MB3660 gateway supports the “agent” mode, which actively and constantly receives data from connected devices.
Updated data is stored in internal memory, which is used to respond to host requests. Although this solution is faster and more efficient, the resulting data will not be the most up to date.
For example, if one request takes 100ms, then 5 connections will cause a delay of at least 100ms x (5-1) = 400ms before the next request is sent. This means that the polling cycle of each SCADA host must be 400ms (plus some tolerance).