Data collection mode

In

Polled

mode, RSLinx Classic generates all requests for data. Polled mode generates a new data packet every time the elapsed time exceeds the polling rate (unless a packet was already sent). In polled mode, DDE does all of the work, so it is easy to make changes and control the communication. Also, no processor programming or ladder program editing is required to set up the conversation. In polled mode, data can be read from or written to a processor in individual pieces or in blocks. Polled mode adds overhead to the Windows application because DDE is always looking for data from the processors. Since RSLinx Classic is constantly polling, the communication traffic volume is higher compared to unsolicited mode

In

Unsolicited

mode, data is sent to RSLinx Classic by a message instruction in the processor. Unsolicited mode waits for a packet from the processor; DDE is essentially waiting in the background until the packet arrives, which keeps the communication traffic down. The advantage of this mode is that messages on the network are generated only when required, reducing the overhead in Windows applications and on the network. Unsolicited mode is a good method of transferring large amounts of data that change infrequently. In unsolicited mode, data can be written from the processor to RSLinx Classic in individual pieces or in blocks. The disadvantage is that unsolicited mode requires ladder programming to set up or change.