Hi.
There are several ways to communicate between Vision PLC's, but using analog I/O's is not one of them (at least not a recommended one). I have a solution for you, based on the following assumptions: 1. Both machines are'nt very far from each other. 2. The PLC's doesn't include the Ethernet module. 3. The industrial machines generate EMI in some level that might interfere with the normal PLC's operation. If these assumptions are correct, i would recommend connecting both PLC's via Modbus over RS485 cable. It is relatively immune to noise and You can define it easily in Visilogic. Define the washing machine PLC as Modbus master, and the dryer PLC as Modbus slave. When the operator input the weight load (on master PLC), send this data to the slave PLC and multiply this value by a factor. I attached to this post two Visilogic application (Modbus Master & Slave). These applications are for V130 but hey demonstrate exactly what you need to add to your application. I also attached a PDF taken from Visilogic help file regarding RS485 network setup.
Hope this helps. For any questions feel free to contact me.
V130_Modbus_Master.vlp
V130_Modbus_Slave.vlp
RS_485.pdf