S.B.C. Elettronica S.p.A. - Engineering Division
HPDxxN – High Power User’s Manual
20
2.12 Serial line connection
The HPD N drive serial line can be configured as RS-422 or RS-485 depending on the
connection. In both cases termination resistors must be used (150
Ω
). Where more than one HPD
N drive is connected to the bus the final node must be terminated as shown below. The two cases
are illustrated in the following diagrams.
TX
RX
/TX
/RX
+BR
-BR
0 V
0 V
MASTER
RS-485
X5
X5
X5
NODE 1
NODE n
LAST NODE
TX
RX
/TX
/RX
+BR
-BR
0 V
0 V
RS-422
MASTER
X5
X5
X5
NODE 1
NODE n
LAST NODE
2.13 Braking resistor
HPD N drives are equipped with an integrated braking resistor. The effective use of the braking
resistor can be checked by monitoring the value of parameter Pr37, which is expressed as a
percentage. If you intend to dissipate more power, use two external braking resistors. To connect up
the system (which must be carried out in conditions of complete safety) disconnect the jumper
between terminals R1 C1 and R2 C2 of terminal board X4; connect one resistor between AB and
C1 and the other between BB and C2 on X4. The external resistor value must be 40 ohm and a
thermal magnetic circuit breaker must be installed between resistor and drive. The minimum wire size
for the connection is 4 mm
2
; the connection cables should be as short as possible and, in any event,
no longer than 3 metres.