AS-interface Masters and Gateways
TURCK offers a wide variety of AS-I masters and gateways manufactured by Bihl+Wiedemann. These devices control communication on the AS-I network and provide a logical connection from the slave and I/O devices in the field to the host. The terms “master” and “gateway” as used here differ in the following way: A master is an AS-I controller that provides a direct link to the host (PLC, PC, DCS etc.); a gateway is an AS-I master, while also being a slave to a higher-level system (such as DeviceNet, PROFIBUS-DP or Ethernet). In the case of a gateway, the AS-I information is compiled by the AS-I master and communicated through the higher-level system as a standard slave data map.
AS-I masters and gateways are available in several different designs. The latest gateway versions incorporate stainless steel housing, support DeviceNet, EtherNet/IP, Modbus-TCP, PROFIBUS-DP, CANopen and Modbus as higher-level networks, and are available with one or two AS-I masters. These gateways also feature AS-I v3.0 software, and a graphical display for configuration and maintenance with no need for a PC. Other new features include a direct serial connection to the AS-I Control Tools software (requires a connection cable that can be ordered with the software: part number ASI-CT-SS BW1602), ground fault detection and duplicate address detection.
Gateways for some higher-level systems are also available with nylon housing. Some of these feature a graphical display, while others contain a two-digit display for configuration. These gateways may be connected to the AS-I Control Tools software through the higher-level network interface by using a “master simulator”.
Masters are available as cards for Allen-Bradley, ControlLogix, CompactLogix and MicroLogix 1500 PLCs, as well as in several different PC control form factors. Stand-alone masters with RS232, RS485 and RS422 serial connections are also available.
AS-I masters and gateways are available with one or two supported AS-I networks, referred to as “single masters” and “double masters”. Double masters can be used to save cost and cabinet space where the system being installed is too large (physically or due to the number of slaves) for one AS-I network. The master and power supply may be connected anywhere along the network, but should be located next to each other. Slaves and repeaters should not be connected between the master and the power supply, as doing so disables some diagnostic features (such as duplicate address detection and ground fault detection). An example of a system with the “A-style” power supply (gateway is powered from the AS-I power supply) is shown here.
Alternatively, two AS-I networks could be connected to one dual master, as shown. The dual master consists of two AS-I masters and one connection to the higher-level system (or backplane). Note that each AS-I network has its own power supply, but combining the two masters into one unit conserves cabinet space. This is the “A2” power supply configuration (gateway is powered from the AS-I supplies for each network).
A third option is to use a dual master with a single power supply (E-style power configuration). In this case, the master contains the necessary AS-I power supply decoupling circuit for each network. Therefore one 30 VDC power supply can be used for both networks saving even more space and product cost. More than one of these double masters can be supplied from the same 30 VDC source.
Network addresses for all AS-I gateways are programmed via the push buttons on the face of the gateway. For more details, please consult the user manual for the specific gateway in question. Manuals are available here, and can be downloaded from the left-side menu above.