Abstract:
An industrial process transmitter 102 for transmitting a process variable on a two-wire process control loop 106 includes, a loop current control 162 to control a loop current level on the two-wire process control loop 106 that is related to the process variable. Power is provided to primary circuitry 164 of the process transmitter 102. A secondary current control circuit 166 limits current delivered to secondary circuitry 168.
Abstract:
A process variable transmitter (100) for use with a removable operator interface (202) has a non-volatile memory (204) and a latching component (210). The non-volatile memory (204) stores device settings (206). The latching component (210) prohibits changes to transmitter settings if the removable operator interface (202) is absent. Circuitry in the transmitter (100) detects the presence of the removable operator interface (202). The removable operator interface (202) can include zero and span settings.
Abstract:
A control system uses a wireless mesh network to provide communication between a host computer and field devices. The host and the field devices communicate with one another using wireless messages containing requests and responses that are routed through the wireless mesh network. The wireless messages include sequence information that allow the receiving device to identify and reject messages that are received out of order.
Abstract:
A host computer communicates with field devices by sending control messages and receiving response messages over a wireless network. When the host computer sends a control message to the wireless network, the host computer is provided with a predictive response time within which the field device receiving the message will respond. The wireless network cycles between a sleep state and an active state based upon a wireless network power cycle. The predicted response time is based upon the current state of the wireless network, the power cycle, and the time required for the field device to turn on, take an action (such as measuring a parameter), and generating a response message.
Abstract:
A field device (14) for use in an industrial process control or monitoring system (10) includes terminals (56H, 56L) configured to connect to a two-wire process control loop (16) configured to carry data and to provide power. In one embodiment, RF circuitry (22) in the field device (14) is configured for radio frequency communication having variable power consumption. In another embodiment, the RF circuitry (22) is coupled to the field device (14) through a separate digital communication bus (100) . A method of modulating the power of RF communication based upon a process communication signal is also provided.
Abstract:
A process variable transmitter (100) that preferably includes a transmitter output circuit (400, 300) that provides bidirectional HART and controller area network communication transceiver lines (LOOP+, LOOP-, CAN, GND). The transmitter output circuit also includes sensor circuit interface contacts (202) . An isolated circuit (201) couples to the sensor circuit interface contacts. The isolated circuit includes sensor circuitry sensing a process variable. The isolated circuit further comprises a galvanic isolation barrier (204) galvanically isolating the sensor circuitry from the HART and controller area network transceiver lines. A stacked power supply (Figs. 9A-9B) provides power management. Other aspects may include a controller area network current limiter diagnostic output (934), timed sequencing of microcontroller startup and shutdown, a local operator interface and power management.
Abstract:
A pressure transmitter assembly (106) for measuring a pressure of a process fluid (104) includes an isolation diaphragm assembly (120). A pressure sensor (130) is spaced apart from the isolation diaphragm assembly (120) to provide thermal isolation. A conduit (122) extends from the isolation diaphragm assembly (120) to the pressure sensor (130) and is configured to carry isolation fill fluid.
Abstract:
A wireless mesh network is formed by nodes (GW1, GW2, A-F, X-Z) having a regular active schedule for transmitting and receiving messages, and a fast active schedule mode that is locally activated when a demand exists for transmission of a larger number of messages. As each node transmits a message to another node, the transmitting node includes a message buffer queue parameter that indicates the number of messages in the transmitting nodes, pending message queue. The receiving node determines, based upon the message buffer queue parameter received and its own capacity, whether to continue on the regular schedule, or to activate the fast active schedule. If the fast active schedule is activated, the receiving node sends a special acknowledge message back to the sending node, so that both nodes will transmit and receive messages over a fast active schedule link until the message buffer of the sending node has been reduced and the fast active schedule can be deactivated in favor of the regular active schedule.
Abstract:
A control system uses a wireless network to provided communication between a host computer and field devices. The field devices are normally maintained in a lower power or sleep state. Only field devices that will be involved in a communication with the host computer are turned On and maintained On until communication between the field devices and the host computer is completed.
Abstract:
A host computer communicates with field devices over a wireless network that includes a gateway and a plurality of wireless nodes. At least one of the field devices is associated with each wireless node, and each field device has a unique field device address. The host computer sends control messages to field devices using their field device addresses. The gateway translates the field device address of a control message to a wireless address of the wireless node with which the field device is associated. The gateway sends a wireless message over the network to the wireless node at the wireless address. The message contains the field device address so that, when the wireless message is received and opened, the control message from the host computer can be routed to the intended field device based upon the field device address.