Rockwell Automation 20-COMM-H RS485 HVAC Adapter FRN 2.xxx - Manual (Page 93)

Glossary G-3
20-COMM-H RS-485 HVAC Adapter User Manual
Publication 20COMM-UM009D-EN-P
H HIM (Human Interface Module)
A device that can be used to configure and control a drive. PowerFlex
7-Class HIMs (20-HIM-xxx) can be used to configure PowerFlex 7-Class
drives and their connected peripherals.
Hold Last
When communication is disrupted (for example, a cable is disconnected),
the adapter and PowerFlex drive can respond by holding last. Hold last
results in the drive receiving the last data received via the network
connection before the disruption. If the drive was running and using the
Reference from the adapter, it will continue to run at the same Reference.
I I/O Data
I/O data, sometimes called “ implicit messages” or “input/output,” is
time-critical data such as a Logic Command and Reference. The terms
“input” and “output” are defined from the controller’s point of view. Output
is produced by the controller and consumed by the adapter. Input is
produced by the adapter and consumed by the controller.
L Logic Command/Logic Status
The Logic Command is used to control the PowerFlex 7-Class drive (for
example, start, stop, direction). It consists of one 16-bit word of output to
the adapter from the network. The definitions of the bits in this word depend
on the drive, and are shown in
Appendix C .
The Logic Status is used to monitor the PowerFlex 7-Class drive (for
example, operating state, motor direction). It consists of one 16-bit word of
input from the adapter to the network. The definitions of the bits in this
word depend on the drive, and are shown in
Appendix C .
N Node Address
Each device on a network must have a unique node address to identify it. On
Modbus RTU, Metasys N2, and Siemens Building Technologies P1 FLN
networks, devices can have node addresses between 1 and 255 if the
network is set up to accommodate that number of devices.
NVS (Non-Volatile Storage)
NVS is the permanent memory of a device. Devices such as the adapter and
drive store parameters and other information in NVS so that they are not lost
when the device loses power. NVS is sometimes called “EEPROM.”
P Parity Check
When the adapter uses a parity check, a non-data bit is added to each binary
word that it sends and receives. Devices on the network verify the data
integrity of the transmitted data by checking that the sum of the number of
ones in a word is always even or odd.