When configuring a device in PL7 Junior Program application, select the Application - Configuration option on the menu to open a window with a device view and click Comm to open a window with communication configuration.

Select the Master type and then select the number of Slaves this Master polls. By definition, this Driver can operate as number 1 (one), 2 (two), or 3 (three). Therefore, the other Slaves must have different numbers. Do not specify a number greater than the number of physically connected devices, to communicate faster, because this Driver waits for a Master to poll numbers 1 (one), 2 (two), or 3 (three) to start transmitting.

The other parameters are 8 (eight) data bits, 1 (one) stop bit, and adjustable parity (default is Odd).