Model 485HF9
Page 10
2.4
Power Requirements
The Model 485HF9 Adaptor must be powered from an external power supply providing a
positive output of between +5.0 VDC and +13.0 VDC. This auxiliary power supply unit should
be capable of sourcing at least 100 mA for each 485 Adaptor that it supplies. Within this
constraint, as many 485 Adaptors as are required can be fed from a single supply. The
Amplicon Mains adaptor meets this requirement and the U.K. version is available under order
code 919 135 69. See paragraph 2.4.1 for information on connecting this mains adaptor to the
Model 485HF9 terminals.
The 485HF9 Adaptor is fitted with an eight way pluggable terminal strip at its free end, and the
power supply should be connected to terminals 7 and 8. Terminal 7 is Ground or negative,
terminal 8 is the positive supply. OBSERVE POLARITY when powering the adaptor. If the
polarity is incorrect, the 485HF9 Adaptor will not operate, but is protected against damage. A
wiring diagram for applying power to a single 485HF9 Adaptor is shown in figure 2.4 and the
connections to multiple, parallel powered 485HF9 Adaptors are shown in figure 2.5.
FIGURE 2.4
POWER SUPPLY CONNECTIONS FOR SINGLE MODEL 485HF9 ADAPTOR
When multiple 485 Adaptors are fed from a single supply as in figure 2.5, the grounds of all the
devices on the RS-422/485 bus will be connected together through the common negative
supply line and the internal ground connections of the Adaptors.
POWER SUPPLY
5.0 to 13.0 VDC
–
+
Model
485HF9
Adaptor
EN
1
GND 2
TX 3
TX
4
RX
5
RX 6
GND 7
VDC 8
Summary of Contents for 485HF9
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