There are two ways to monitor the communication between InTouch and the PLC. The first way is by using items (bits) congenital IO/DA Servers are $SYS$ status (DA Server) or Status (IO Server) and the IO status. The second way is by making to use PLC Heartbeat InTouch scripting engine.
Each of these ways has a weakness, because if you rely on just the first way, there is still a gap in which it can not provide information about the status of the PLC (STOP / RUN). The second way is powerful enough to monitor InTouch-PLC communication. The problem, if not combined with bits and IO Status it difficult to determine who the real cause of this communication error, if the IO/DA server, cable connection or even its PLC-STOP. To overcome these weaknesses is to combine both of the ways.
How IO Status bit, Status ($SYS$ Status) and PLC Heartbeat monitor the status of communication between InTouch, IO/DA Servers and the PLC can be described as follows:
1. Bit Status ($SYS$ Status) is an innate IO/DA Servers, serves to monitor the status of communication between the IO/DA Servers with PLC.
2. Bit is also innate IO Status IO/DA Servers, serves to monitor the status of IO/DA Servers itself. These bits can also be used to monitor communications between two nodes with InTouch or InTouch DDE support for programs such as Microsoft Excel.
3. PLC Heartbeat is used to monitor the data communication between the PLC- InTouch.