The recently launched T2 Maxiflex CPUs are designed specifically for data acquisition and telemetry applications like custody transfer systems. They require no user application programs when used for data acquisition or telemetry application, making them the ideal equipment for this type of system. One plugs them in, connects the field wiring and powers up. All the I/O is scanned automatically and I/O status assembled into Data Interchange Table (DIT).
Using a technique called 'network subscriptions' (same idea as subscribing to a magazine from the newsagent) the data at either end of the custody transfer system can share the data between themselves. This is done on time interval basis for analogs and change of state for digitals. This is achieved without writing one line of program code. Maxiflex is configured using a Windows-based Configuration Management Package which edits the Maxiflex DIT table and invokes the network services necessary to implement the data transfer between either end of the custody transfer system. These configuration files can be saved and stored on the PC/laptop. Configuration can be done at the unit itself or via the network, which is especially useful when access to the other end of the system is difficult. These tools also facilitate browsing of the system for engineering staff.
The system integrates the required parameters of a custody transfer system together. Being modular and flexible, Maxiflex can accommodate systems with primitive front end instruments right up to sophisticated measurement devices with on board communications ports, eg, RS232/RS485, Modbus, HART, Ethernet. Maxiflex has been used with simple pulse output metering to sophisticated devices or even analytical equipment fitted to pipelines. The telemetry aspect of the custody transfer system is often the most crucial and difficult element; Maxiflex Networks can be implemented on copper cable (screened twisted pair - instrument cables) up to 10 km between the custody transfer measurement points. Radio systems can be used for wireless applications where cable infrastructure is non-existent or cabling costs are prohibitive. Other network media such as fibre-optic cable etc, can also be used.
Configuration is easily made using a free Windows-based software package called 'OmniSet' (Figure 1) and a serial cable available from Omniflex. Additional Configuration Management packages that are more feature-rich are also available to cater for the needs of the end-user's system. Simple selection of pull-down options allows the user to configure the CPU. This configuration includes the ability to create multidrop telemetry systems using the Omniflex CONET Local Area Network up to 10 km on twisted pair cable.
Maxiflex provides a cost-effective solution to custody transfer applications and simplifies the field I/O systems by eliminating the need to write time-consuming application programs for data acquisition or telemetry (Figure 2). Should some control be required, this can be integrated within the system as an application program. Maxiflex I/O systems cover analog inputs, voltage, current, thermocouple, RTD and digital inputs, potential free and voltages up to 200 V d.c., series contact chains, pulse inputs up to 50 kHz. Many flowmeters have HART protocol on board and this can be wired directly into the Maxiflex System via a HART Network Interface module. This has the benefit of allowing the entire spectrum of data on the flowmeter to available to the system.
Integration into commercial systems for billing purposes is easily achieved from PC systems and all network data can be made available through the use of Windows operating system OPC servers to which the commercial systems become clients to retrieve the data.
For more information contact Ian Loudon, Omniflex, 031 207 7466, [email protected], www.omniflex.com
| Tel: | +27 31 207 7466 |
| Fax: | +27 31 208 2058 |
| Email: | [email protected] |
| www: | www.omniflex.com |
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