Data acquisition gets active
28 Nov 2006
The increase in processing power of industrial PC's is making a major impact in DAQ
Data acquisition customers have to date been mainly interested in building test systems for post production testing, using data acquisition cards inside industrial PCs. However with the increase in processing power of industrial PC's, they have more recently been adopted for factory automation and process control applications instead of PLCs or large DCS systems.
Initially RS485 serial communications provided the link between remote data acquisition modules and the PC, but there has been a significant transition towards IP based I/O (input/output) as customers expand their industrial Ethernet infrastructure.
Amplicon, for one, has seen 68% growth in sales of remote data acquisition modules that use Ethernet for communications in the 12 months to 30 Sept compared to the previous 12 months.
In both serial and Ethernet based I/O modules, the method of data collection is typically as follows; the PC sends a request to a passive remote data acquisition module asking for readings on the input channels, and the module sends a reply.
Whether this is done over RS485 or Ethernet, the time to respond can be up to 1 second, which is often acceptable for many SCADA systems.
Many customers are investing in "real-time" or fast acquisition systems that include an embedded PC running Linux or Windows CE with a PCI card inside. Alternatively, they install a dedicated system such as the TopMessage — a stand-alone data acquisition system that can process and store results, independent of a PC (similar to a data logger).
Typically these systems are much more expensive and could be more powerful than is actually required and alternatives are now available.
The latest "Active ioLogik" remote I/O servers from Moxa, for example, can send a message to the host PC when a change of state occurs, so the information is effectively real-time. For example if someone triggers a door switch fitted, it can change the digital input on channel #1 from 0 to 1 (from low to high).
The event is read by the Moxa E2210 which then sends a message using TCP or UDP over Ethernet, to the host PC or client, or an email to the site manager. For customers who use SNMP software such as HP OpenView, the device can use SNMP traps instead of TCP messages. This alert mechanism is significantly faster than traditional poll/ respond cycle times.
The Active ioLogik range can also perform logic functions on-board, via AND/OR commands in a "If x then y" structure. Up to three inputs can be monitored using AND or OR to control up to three outputs, or messages. This results in much faster processing within the ioLogik E2210, instead of using a PC to perform the logic control function.
A Windows-based tool is used to set up the ioLogik range, including functions such as what the outputs should do after power up, or if communications fail. The built-in web browser provides access to all I/O conditions and settings but not the "Click and go Logic" programming. Another feature is IP security, which lets users enter a list of 10 approved IP addresses, to prevent unauthorised access.
Initially RS485 serial communications provided the link between remote data acquisition modules and the PC, but there has been a significant transition towards IP based I/O (input/output) as customers expand their industrial Ethernet infrastructure.
Amplicon, for one, has seen 68% growth in sales of remote data acquisition modules that use Ethernet for communications in the 12 months to 30 Sept compared to the previous 12 months.
In both serial and Ethernet based I/O modules, the method of data collection is typically as follows; the PC sends a request to a passive remote data acquisition module asking for readings on the input channels, and the module sends a reply.
Whether this is done over RS485 or Ethernet, the time to respond can be up to 1 second, which is often acceptable for many SCADA systems.
Many customers are investing in "real-time" or fast acquisition systems that include an embedded PC running Linux or Windows CE with a PCI card inside. Alternatively, they install a dedicated system such as the TopMessage — a stand-alone data acquisition system that can process and store results, independent of a PC (similar to a data logger).
Typically these systems are much more expensive and could be more powerful than is actually required and alternatives are now available.
The latest "Active ioLogik" remote I/O servers from Moxa, for example, can send a message to the host PC when a change of state occurs, so the information is effectively real-time. For example if someone triggers a door switch fitted, it can change the digital input on channel #1 from 0 to 1 (from low to high).
The event is read by the Moxa E2210 which then sends a message using TCP or UDP over Ethernet, to the host PC or client, or an email to the site manager. For customers who use SNMP software such as HP OpenView, the device can use SNMP traps instead of TCP messages. This alert mechanism is significantly faster than traditional poll/ respond cycle times.
The Active ioLogik range can also perform logic functions on-board, via AND/OR commands in a "If x then y" structure. Up to three inputs can be monitored using AND or OR to control up to three outputs, or messages. This results in much faster processing within the ioLogik E2210, instead of using a PC to perform the logic control function.
A Windows-based tool is used to set up the ioLogik range, including functions such as what the outputs should do after power up, or if communications fail. The built-in web browser provides access to all I/O conditions and settings but not the "Click and go Logic" programming. Another feature is IP security, which lets users enter a list of 10 approved IP addresses, to prevent unauthorised access.
