cDAQ-9183 Overview

The four-slot cDAQ-9183 Ethernet chassis is designed for use with C Series modules. The cDAQ chassis are capable of measuring a broad range of analog and digital I/O signals and sensors. For module specifications, refer to ni.com/docs for your C Series module.

cDAQ-9183 Key Features

The cDAQ-9183 is a CompactDAQ Ethernet chassis that has the following features and capabilities.

  • Four-slot design that can accommodate up to four C Series I/O modules
  • TSN-enabled for highly distributed measurements over long distances
  • Internal network interface with one ethernet port
  • 32-bit general-purpose counters/timers, accessible through a hardware-timed digital C Series module, for applications involving quadrature encoders, PWM, and pulse train generation
  • Ethernet connectivity for easy integration into existing network infrastructures

System Health Monitoring and User Watchdog

NI recommends the use of system health monitoring and a user watchdog to ensure potential problems are detected and resolved as soon as possible. The cDAQ-9183 has hardware and software features your application can use to monitor system health and respond to events such as hardware faults, software failure, system crash, or any loss of communication. In addition, a user-programmable watchdog can be enabled to either notify your application, reset your application, or reset the chassis in the event an error occurs. For more information on how to configure your system to monitor system health and enable a user watchdog, visit ni.com/
info and enter systemhealth.

Time-Based Features

The cDAQ-9183 chassis features automatic network-based synchronization with compatible networks and IEEE 802.1AS-capable NI Linux Real-Time controllers. The SYNC logo on the chassis front panel indicate that the chassis are capable of hardware-based synchronization over a network.

The chassis supports IEEE 802.1AS synchronization, and all chassis timebases will be automatically synchronized. Refer to Networking and Synchronization across a Network for more information about supported topologies and other technical requirements.

Network-synchronized chassis can also take advantage of time-based synchronization features in NI-DAQmx. Certain triggers and timestamps can be specified in terms of time of day. Time-based triggers and timestamps and multichassis tasks (spanning multiple network-synchronized cDAQ chassis) can help simplify programming for large systems.

Time triggers and timestamps can be specified in Host Time or I/O Device Time, depending on the needs of your application.

  • I/O Device Time—The time the cDAQ-9183 uses internally. This time is determined by the network configuration and is shared by all 802.1AS network-synchronized devices on your subnet.
  • Host Time—The time on your Windows computer or NI Linux Real-Time controller. This is usually the current global time, and is provided by a local real-time clock or a network time protocol (NTP) server.

NI-DAQmx automatically translates from Host Time to I/O Device Time as necessary. The accuracy of this translation depends on the relationship between these times and can reduce the relative accuracy of time triggers and timestamps across multiple devices. For maximum accuracy, use an NI Linux Real-Time controller as the host in a supported topology. However, NI-DAQmx guarantees that two tasks configured to start at the same host time always start at the same I/O Device Time in all scenarios, preserving precise synchronization between chassis in this common use case. Refer to the Timing and Triggering topic in the NI-DAQmx User Manual for more information on accessing time-based features in the NI-DAQmx API.

Watchdog Timer

The watchdog timer is a software-configurable feature used to set critical outputs to expiration states in the event of a software failure, a system crash, or any other loss of communication between the application and the cDAQ chassis.

When the watchdog timer is enabled, if the cDAQ chassis does not receive a watchdog reset software command within the time specified for the watchdog timer, the outputs go to a user-defined expiration state and remain in that state until the watchdog timer is disarmed by a device reset. After the watchdog timer expires, the cDAQ chassis cannot perform any operation until the cDAQ chassis is reset.

You can use the watchdog timer to do the following:

  • Set a timeout period to specify the amount of time that must elapse before the watchdog timer expires
  • Set to expire upon loss of network connectivity

The counter on the watchdog timer is configurable up to (232 - 1) × 25 ns (approximately 107 seconds) before it expires. Analog output, digital output, and counter output channels can be configured to transition to an expiration state when a watchdog timer expires.

Resetting the chassis after a watchdog expiration event results in all module outputs defaulting to power up or startup states as defined in the module specifications.

Note Resetting the chassis after a watchdog expiration event may result in undefined transient behavior on the outputs of the NI-9269 and NI-9474 modules. Consult the module specifications for the expected I/O behavior.
Note Restarting or re-reserving the chassis may lead to undefined transient behavior on the outputs of any modules, so these operations are not recommended as means of a watchdog expiration event recovery.
Note No other operations may be running on the cDAQ chassis while the watchdog timer task is being started; this includes all DAQmx tasks, calibration of modules, and routing and configuration of signals on the chassis. After the watchdog timer task starts, DAQmx tasks can be started and stopped and other operations can be performed.

Firmware

Firmware can be updated through the Hardware Configuration Utility, NI MAX, or the web interface to the chassis. For cDAQ firmware information and updates, visit ni.com/info and enter the Info Code cdaqfw.