Communication Chain Examples

All connections take one of the following forms. Terms used in this illustration are defined in the following table.

Native Serial Driver supports native serial communication as defined in protocol standard documents on PC serial ports using VTScada Serial Port tags.
Modem Driver supports native serial communication as defined in protocol standard document(s) over modems defined in the operating system.
Native TCP/IP Driver supports native TCP/IP communication to devices as defined in the protocol standard documents.
TCP/IP Tunnel Driver supports tunneling of serial protocol via Ethernet connected TCP/IP to serial converters using VTScada TCP/IP Port tags.
Native UDP/IP Driver supports native UDP/IP communication to devices as defined in the protocol standard.
UDP/IP Tunneled Driver supports tunneling of serial protocol via Ethernet connected UCP/IP to serial converters using VTScada UDP/IP Port tags.
Other Connection Driver supports device or protocol-specific interface or methodology not covered by these definitions.
(For example, ODBC.)
Virtual PLC Driver supports VTScada acting as a memory-mapped PLC or RTU that other devices can read from or write to.

 

Common Arrangements

A few common arrangements follow. Many more are possible. Note that the driver tags in each example need not be all the same type.

Scenario 1:

VTScada I/O server with wired IP connection to field device transceiver with static I/P.

Scenario shown based on the use of a typical polling protocol such as Modbus, DF1 or ENIP/CIP

 

Scenario 2:

VTScada I/O server with wireless IP connection to field device transceiver with wireless static IP.

  1. Scenario shown based on use of typical polling protocol such as Modbus, DF1 or ENIP/CIP.
  2. The polling group may be excluded except in one of the following scenarios:
  • Where all data from each field device is to be read at the same time, such as in a single block read (e.g. to minimize communication costs). In this case, the poll rate in the polling driver overrides the scan rate of the associated I/O tags.
  • Where the field devices are to be polled in sequence, in which case the polling group ID must be the same for all devices.
  • Where different protocols (driver tags) are used to communicate with different field devices.

 

Scenario 3:

VTScada I/O server with serial connection to field devices.

  1. Scenario shown based on the use of a typical polling protocol such as Modbus, DF1 or ENIP/CIP.
  2. If configuring the system for redundant I/O servers, use a serial to Ethernet converter to place each field device on an Ethernet connection
  3. If using COM port redirection software, continue to use Serial Port tags. Otherwise, use TCP/IP tags.

 

Scenario 4:

VTScada I/O server with wireless connection between base station transceiver and field devices.

  1. Scenario shown based on the use of a typical polling protocol such as Modbus, DF1 or ENIP/CIP.
  2. Polling group may be excluded except in one of the following scenarios:
  • Where all data from each field device is to be read at the same time, such as in a single block read (e.g. to minimize communication costs). In this case, the poll rate in the polling driver overrides the scan rate of the associated I/O tags.
  • Where the field devices are to be polled in sequence, in which case the polling group ID must be the same for all devices.
  • Where different protocols (driver tags) are used to communicate with different field devices.
  1. If configuring the system for redundant I/O servers, use a serial to Ethernet converter to place each field device on an Ethernet connection

 

Scenario 5:

VTScada I/O server with dial-up modem connection to field devices.

  1. Scenario shown based on the use of a typical polling protocol such as Modbus, DF1 or ENIP/CIP.
  2. Polling group may be excluded except in one of the following scenarios:
  • Where all data from each field device is to be read at the same time, such as in a single block read (e.g. to minimize communication costs). In this case, the poll rate in the polling driver overrides the scan rate of the associated I/O tags.
  • Where the field devices are to be polled in sequence, in which case the polling group ID must be the same for all devices.
  • Where different protocols (driver tags) are used to communicate with different field devices.
  1. If configuring the system for redundant I/O servers, each server must have access to a modem.
  2. Multi-modem (pooled) configurations supported.