Progamming can be monitored or transferred using either port A or port B through communications with this Visual KV Series KV-16AR. Only the KV-16xx, KV-24xx, and KV-40xx have these serial ports for transferring of programming. What is great about the Keyence Visual KV Series units are that you can connect 2 peripheral units. This is possible because the Visual KV Series basic units have 2 serial ports, which improves the debugging of the environment. There are precautions that need to be taken when using these serial ports. Only certain Keyence Visual KV Series Units have the option for two serial ports. They have two RJ-11 connectors for communication. Do not connect a ladder software to the two serial ports simultaneously, while using a handheld programmer. Disconnecting a modem and using a different communication port is required if your personal computer is assigned to a modem with a communication port. The programming manual can help with these Keyence Visual KV Series PLC's. The manuals can also help with the ladder builder for the Visual KV Series Units, there is a Ladder Builder CD-ROM and a connection cable. Please read the manual before attempting to use the Ladder Builder. There are features and configurations of the Ladder Builder that need to be studied before using. Be sure that the model supports Windows 3.1 or later, with an interface of RS-232C and is compatible with IBM PC and PC/AT. The Ladder Builder needs a CPU memory capacity of i486DX2 or more for this Visual KV-16AR.