Ethernet bolsters handling system

01 February 2008

When a major commuter railway, in New York, USA, looked to modernise a 20-year-old material handling system it turned to a well-established systems integrator (SI). The SI opted to choose an industrial-grade, Ethernet managed fibre optic switch from Contemporary Controls. The EICP8M-100T/FC switch, from the company, which has its UK base in Coventry, was employed to connect the control equipment to the network.

Figure 1
Figure 1

The maintenance facility has 14 parallel tracks inside the building and each one can accommodate six cars at a time. Maintenance, upgrades, commissioning and decommissioning are performed at this facility.

Within the facility, seven subsystems comprise a fairly complicated automated material handling system. Six subsystems work together allowing parts and supplies needed for train maintenance to be received, stored and delivered to the appropriate area of the facility when required.

The seventh subsystem, the train movement alarm system, manages the movement of train cars in and out of the facility.

The SI senior lead engineer said modernisation of the system was necessary. ‘It was primarily driven by the difficulty of getting service for control equipment and the inability to purchase replacement parts. Among other things, the customer’s requirements of the system had changed, much of the material handling equipment such as the storage/retrieval machines was worn out and there was an overwhelming desire to take advantage of the new technology.’

While the project was implemented the material handling system remained in operation. A detailed schedule was created to modify individual pieces or subsystems on off-shifts and scheduled periods of downtime.

All communications between the subsystems and manager computers had to use the customer’s existing WAN. Manager computers, responsible for parts inventory and daily work schedules, are located at a remote facility, three to five miles away. They also issue requests to the material handling system to store, retrieve and move parts.

The SI replaced the existing data highway communications between the PLCs and computers with EtherNet/IP technology.

Outdated PLCs were replaced and HMIs were installed to aid in troubleshooting and maintenance.

The engineer claimed large distances, in the facility, dictated the use of fibre optics and this was why an 8-port fibre optic switch from Contemporary Controls was used.

The fibre optic switch answers the call for immunity to EMI/RFI and in delivering transmissions over longer segment distances, up to 2km. This results in decreased downtime, fewer outages and improved reliability.

‘Its compact size and DIN-rail made it easy to install in the control cabinets,’ added the engineer.

Designed with the conventional features in standard Plug-and-Play (PnP) switches, this switch includes important benefits such as IGMP snooping and query functionality, VLAN, Quality of Service (QoS), port mirroring, rate limiting, port security, and the Simple Network Management Protocol (SNMP).

IGMP snooping automatically limits IP multicast traffic to ports that require this traffic. This inhibits multicast traffic from overwhelming devices that should not receive this traffic.

In this application, requiring maximum uptime for the communication network, the switch offers three possible redundancy solutions: RapidRing, Trunking and RSTP (Rapid Spanning Tree Protocol).

Configuration is accomplished through a web browser via any Ethernet port or by using the terminal mode via the local console port. Port parameters, feature configuration, and device status can be modified and monitored by these access methods.

This is a large facility and individual subsystems are spread out over the area. Each subsystem has at least one PLC and one HMI connected to the network. An EICP8M-100T/FC switch is installed in each of the control cabinets to connect the equipment to the network. The communications diagram (figure 1) is of the train movement alarm system. The seven PLC panels house remote I/O. An HMI is located in each PLC panel. Three of the new seven PLCs have remote I/O of various types, which are not in the PLC enclosure. The Ethernet switch is inside the PLC enclosure. Various segment lengths of fibre optic cable make the connection.

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