National Instruments 778981-01 Serial Interface Device

Part Number 778981-01 is the identifying part number for the National Instruments PCI-8431/4 Serial Interface Device. This device is mainly used for reliable serial connections spanning longer distances in industrial and commercial settings. The 778981-01 is a non-isolated 4-port device that supports RS-422 and RS-485 protocols and has baud rates ranging from 57 baud to a maximum rate of 3 Mbps. Note that the baud rates can be configured by the user using MAX (Measurement and Automation Explorer) or the Windows Device Manager or it can be programmed to a certain value using the NI Serial API. The operating rated voltage for the RS-485 standard ranges from -7 V to +12 V. Likewise, the size of the featured FIFO buffer is 128 bytes.

The 778981-01 measures (4.2 × 5.6 in.) in physical dimensions and weighs 102 g. It contains a 10-position modular jack as the I/O connector. As for the power requirement from the PCI channel, the module typically draws 725 mA of current at +5 VDC supply and this can reach a maximum of 1.1 A. The device is recommended for use between the 0 to 55 °C temperature range at a relative humidity of 10 to 90%. On the other hand, it can be stored at a much wider range of –20 to 70 °C at a relative humidity range of 5% to 95%. Note that the 778981-01 is designed for indoor use only and should be mounted inside a sealed enclosure for outdoor use. Likewise, the maximum altitude for the operation of the module is 2000 m. 

In the 778981-01, the maximum cable length for proper operation under RS-485 is 30m, which is limited by EMC/surge, as it is capable of 1.2 km without surge limitation. Moreover, the data line ESD protection for the module, according to the human body model, is ±15 kV. The module meets the requirements of the following safety standards as electrical equipment for measurement, control, and laboratory use: IEC 61010-1, EN 61010-1, UL 61010-1, and CSA 61010-1.