In the past Amplicon’s customers were 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 been adopted by many customers for factory automation and process control applications instead of PLCs or large DCS (Distributed Control 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. At Amplicon we have seen a 68% growth* of remote data acquisition modules that use Ethernet for communications. 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.
We are often asked for “real-time” systems or fast acquisition systems, and can offer an embedded PC running Linux or Windows CE with a PCI card inside. Alternatively a dedicated system such as the TopMessage can be used. This is a stand-alone data acquisition system that can process and store results, independent of a PC (similar to a data logger). Typically a system like this is much more expensive and could be more powerful than is actually required.
Amplicon have just introduced the next generation of remote I/O servers from Moxa. These “Active ioLogik” servers are able to send a message to the host PC when a change of state occurs, so the information is effectively real-time. For example if someone opens a door which has a door switch fitted, it can change the digital input on channel #1 from 0 to 1 (from low to high). This event is read by the Moxa E2210 which then sends a message using TCP or UDP over Ethernet, to the host PC or client. Alternatively it can send an email to the site manager or anyone else with an email address. For customers who use SNMP software such as HP OpenView, the Moxa E2210 can use SNMP traps instead of TCP messages. This alert mechanism is significantly faster than traditional poll/ respond cycle times.
In addition to Active messaging, the Active ioLogik range has the ability to perform logic functions on-board. This uses 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 (as detailed in the previous paragraph). This results in much faster processing within the ioLogik E2210, instead of using a PC to perform the logic control function.
A Windows based admin 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 not seen on other Ethernet I/O devices is IP security. This lets the user enter a list of 10 approved IP addresses, to prevent access by unauthorised people.
One recent application was for a tunnel monitoring system. Inside the tunnel are various communication and monitoring devices. They are located inside instrument rooms at regular intervals along the tunnel. Each instrument room has up to 40 pieces of equipment in 19” rack mount cabinets, all of which have status monitors that produce an alarm signal if they detect a problem. The 40 alarm signals are connected to a server which can generate an email or notify site engineers to go and investigate when there is a problem. This is in addition to the main purpose of the server which is to control the communications and monitor the environment. There are four instrument rooms in this particular tunnel which means a total of 160 alarm status lines had been wired along the length of the tunnel, back to the server.
The customer was concerned about the confusion of 160 cable needed for alarms, in addition to all the other cables which include Ethernet and power signals. We proposed the ioLogik E2210 which has 12 digital (status) inputs per module and Ethernet communications. This means four ioLogik E2210s are required to monitor the 40 items in each instrument room. We also specified a Garrettcom 8 port switch for each Instrument room, to connect the four E2210 and convert the Ethernet signal to fibre optic for transmission to the server. These four switches also provide a fully redundant ring network for complete reliability. Each ioLogik is programmed so that if an alarm condition is received on any channel, it sends an email to the on-call engineer advising that there is a fault condition. It automatically identifies which item has alarmed and at what time. So the E2210 significantly reduces cabling (and provides a tidier solution), while also improving response time and communications to the Service Engineer.
*Growth figure based on 12 months sales up to 30th September 2006 compared to the previous 12 months.