Modbus/TCP Driver - Internal Data Points

_Mod_Plc

Data point element Type Default Range Description
PlcNumber unsigned - 0..65535 Identification number of a PLC for the driver.
HostsAndPorts dyn_string "" - Contains the host names or IP addresses or the port numbers for the TCP connection.
UnitAddress unsigned 0 0..255 Number of Modbus unit or Slave address.
TransactionTimeout int 1000 - Timeout between the request and response in milliseconds.
Coding unsigned 1 1,2,3

Defines the coding of the Modbus frame.

1 -> TCP

2 -> ASCII

3 -> RTU
SetInvalidBit bool 0 0|1 Defines if the invalid bit should be set if the driver loses the connection to the PLC.
RedundantPlc bool 0 0|1 Name of the redundant PLC if one exists.
ReduHostsAndPorts dyn_string - - Contains the host names or IP addresses resp. the port numbers for the TCP connection in case of a redundant PLC.
ReduUnitAddress unsigned 0 0..255 Number of Modbus unit or Slave address for a redundant PLC.
ConnState unsigned - - Indicates whether a PLC is connected or not.
Error unsigned - - Indicates the last error of the driver (the error code).
SentFrames unsigned - - Number of requests that should be transmitted to the unit.
RcvFrames unsigned - - Number of requests that should be received from the unit.
RejFrames unsigned - - Number of discarded requests.
Active bool 1 0|1 Specifies whether the drivers communicates with the corresponding PLC (TRUE) or not (FALSE).
Offset unsigned 0 - In some Modbus devices there is an offset between the internal addressing and the addressing in the protocol (e.g. in case of a Schneider Quantum device the internal address 1 relates to the protocol address 0). This data point element allows to define the offset. Thus a device-specific configuration is possible (in case of the Schneider Quantum the value would be 1).
ConfigFlags bit32 0 -

Bit0 of this data point element defines the behavior of the "only active driver" option.

  • 0: default behavior, both drivers establish connection
  • 1: only the active driver connects to the PLC

Bit1 defines the timestamp mode for float transformations.

  • 0: timestamp with milliseconds
  • 1: timestamp without milliseconds

Bit 2 defines the endianness of the register:

  • 0: Little-endian
  • 1: Big-endian

Bit 3 defines, if the config entry [mod] littleEndianRegister or the settings of the data point should be preferred.

  • 0: The settings of the config entry are preferred.
  • 1: The settings of the data point element are preferred.

Bit 4 defines, if the bytes within the drivers should be swapped.

  • 0: The bytes are handled without swapping.
  • 1: The bytes are swapped.

UserFC64.Request

UserFC64.Response

UserFC64.State

 - - These 3 data point elements are only relevant for a specific device and are not for general use. Thus they are not described in detail.
UserWriteWithPwd.Password

The Siemens PAC devices possess modified write function codes. At the end of a telegram, a 2 byte password is sent.

A password can be specified for this (UserWriteWithPwd.Password) password datapoint element of the _Mod_Plc datapoint.

If the element is empty, the telegram is written normally.

If you specify a password, the telegram is written with a modified function code and a 2 byte password.

Note: The password is stored and transmitted unencrypted.