Internal connection is meant for the communication between various objects inside application. For example, output from one Simulation object can be transferred to the input of another.
Connected/disconnected status of Connection and access state of Item exist only for imitation purposes.
Internal Item may contain values of type Boolean, Byte, SByte, Int16, Int32, Int64, UInt16, UInt32, UInt64, Single, Double, Decimal, Char, String, DateTime and one-dimensional arrays of these types.
Modbus connection is meant for communication using Modbus protocol.
“Errors before disconnect” property regulates how many errors (for example, timeouts) will pass until connection will be automatically disconnected. If value is zero – disabled.
MQTT connection is is meant for communication with MQTT broker (IoT). Connection is based on M2Mqtt library - open source realization of MQTT client (https://m2mqtt.wordpress.com/).
OPC connection allows data communication with OPC DA server.
Some OPC servers can`t hold high load. Option “Use synchronous write” helps to avoid this limitation, sometimes. Please note, that this option makes simulation cycle longer.
There is no standard way how OPC server wants client to address OPC item. Options “Use access path”, “Separator” and “Ignore root” are meant for simplifying Item creation according to demands of concrete server.
OPC UA connection allows data communication with OPC UA server.
S7IsoTCP connection is meant for communication with Siemens PLCs: S7-300 and S7-400 (1200/1500 are also partially supported). Connection is based on Snap7 library - open source realization of S7 Protocol (http://snap7.sourceforge.net).
“Errors before disconnect” property regulates how many read/write errors will pass until connection will be automatically disconnected. If value is zero – disabled.
“Slowdown” value is meant for regulating CPU load and is inversely proportional to it.
S7PLCSim connection is meant for communication with Siemens SIMATIC S7PLCSim V5.4. Writing and reading of DB and М memory, writing of I and reading of Q, are supported.
"Slowdown" value is meant for regulating CPU load and is inversely proportional to it.
In case of connection problem, try to run TIAPortal/Step7 as administrator.
In case of problem with Q reading, when communication is working well with other memory areas, try to load hardware configuration to S7-PLCSim.