System limits 
3 
NK823x system limits 
16 
Building Technologies    A6V10062437_a_en
Fire Safety & Security Products    30.06.2013
3.4  NK823x system limits 
Network capabilities (upstream towards management system host) 
  2 Ethernet interfaces IEEE 802.3, 10/100 Base-T with auto-negotiation, half/full-
duplex with auto-sensing, auto-crossover (thus eliminating the need for crossover 
cables) 
  Single host transport protocols: 
–  CEI 79-5 type A and B, optional FEAL 64-bit encryption (NK8231, NK8232 and 
NK8235) 
–  CMSDL/IP (NK8232 and NK8235) 
–  BACnet/IP (NK8232 and NK8235) 
  Multiple hosts (max four hosts combined in total), transport protocols: 
–  Max. 4 CMSDL/IP (NK8231, NK8232 and NK8235) 
–  Max. 4 BACnet/IP (NK8232 and NK8235) 
–  Max. 3 Modbus TCP/IP (NK8232 and NK8235) 
  Redundant connectivity to hosts (dual Ethernet), transport protocols: 
–  CMSDL/IP (NK8232 and NK8235) 
–  CEI 79-5 type A and B, opt. FEAL 64-bit encryption (NK8232 and NK8235) 
  DHCP is currently not supported. A static IP address is required. 
  SNMP supported for remote monitoring; NK823x units can provide a basic set of 
public information as well as an advanced engineering report. 
Serial capabilities (downstream towards subsystems and upstream 
towards local management system host) 
NK8235: The maximum number of serial lines is 4, allowing connection up to 4 local 
units (intrusion, access control, fire, gas detection, CCTV control units). Two serial 
lines are available on the mainboard and two on an expansion module. The serial lines 
can also be used for a local host, a dial-up host or a Modbus RTU connection to a 3rd 
party Modbus master device. 
 
 
Note: The two serial lines on the expansion module (COM3, COM4) do not support 
the hardware-handshaking signals for modem control (Rx, Tx, and GND only). 
NK8232: The maximum number of serial lines is 2 (on the mainboard). Only one 
connection to a local unit (intrusion, access control, fire, gas detection, CCTV control 
units) is allowed. The second line can be used for a local host , a dial-up host or a 
Modbus RTU connection to a 3rd party Modbus master device. 
NK8231: The maximum number of serial lines is 2 (on the mainboard). Only one 
connection to a local intrusion unit is allowed. Only one Ethernet interface with CEI 79-
5 upstream protocol is supported (no redundant connectivity to hosts). 
In all NK823x models, two serial ports can be configured as an RS232 interface using 
connector COM1 and COM2, or as an RS485 interface using connectors X104 and 
X105. The NK8235 RS485 interface can handle up to 32 Modbus devices. 
LON bus connectivity 
LON bus connectivity for CS6 Guarto is not supported on NK823x.