Chapter 3 – Electrical Installation
ACA 6xx Sections and ACS/ACC 6x7 (132 to 3000 kW) Frequency Converters   3-35
• one Control Panel is chained to many drive units
RS-485 Termination
Settings
When the Control Panel CDP 312 is connected to one NAMC-21/22 
board only, the RS-485 line must be terminated on the NAMC-21/22 
board by jumpers X5 as follows:
If CDP 312 is connected to several NAMC 21/22 boards (RS-485 panel 
bus), the first and the last NAMC 21/22 board must be terminated. The 
intermediate boards must not be terminated.
X3
X2
X1
X1
CDP 312
NDPI-21
X4
X3
X4
X3
NAMC-21/-22
X4
X3
X4
X3
X4
X3
[N-1]
[N]
[3]
NAMC-21/-22
[2]
[1]
NAMC-21/-22
NAMC-21/-22
NAMC-21/-22
The CDP 312 Control Panel can be 
connected (through NDPI-21 or 
directly) to the NAMC-21/22 board to 
the 6-pin modular connector X3. The 
modular connectors on the NIOC 
board are not intended for the Control 
Panel.
The maximum cable length between 
CDP 312 (or NDPI-21) and NIOC-01 or 
NAMC-xx is 10 metres. In the 
presence of high-level radiofrequency 
disturbances, the length should be 
limited to 3 metres.
The maximum total length of the panel 
bus is 30 metres. With Panel Bus 
Connection Interface Module NBCI-01 
the maximum panel bus length can be 
extended to 1200 metres (refer to 
NBCI-0x Module Installation and Start-
up Guide)
RS-485 panel bus
Control Panel cable
Max. 31 pieces
Terminated
Terminated
Not terminated
Not terminated
Not terminated
Fixed 
termination
No termination
Terminated
Not terminated