Honeywell CIPer 50 Installation & Commissioning Instructions page 9

RS485-1 Bias and Termination Resistors
RS485-1 is equipped with a three-position slide switch
which can be used to switch its bias resistors OFF (position
"MID" – this is the default), ON (position "BIAS"), and ON
with an additional 150Ω termination resistor (position
"END").
3-POSITION SLIDE SWITCH
Fig. 13. RS485-1 three-position slide switch
The recommended slide switch setting depends upon the
location and usage of the given CIPer Model 50 – see Fig.
14 through Fig. 16 and Table 5; it also depends upon the
selected communication protocol (BACnet MS/TP, Panel
Bus, or Modbus RTU Master communication, respectively).
Table 5. Recommended slide switch settings
setting
Controllers located on either end of bus should
END
have this setting.
In small bus networks, a min. of one and a max. of
BIAS
two controllers should have this setting.
All other controllers (not set to "END" or "BIAS") on
MID
bus should have this setting (which is the default).
MID (DEFAULT)
RS485-1 (+)
RS485-1 (-)
Fig. 14. RS485-1 three-position slide switch setting MID
CIPer MODEL 50 CONTROLLER – INSTALLATION & COMMISSIONING INSTRUCTIONS
RS485-1
remarks
+5V
ISO
47 kOHM
47 kOHM
GND-1
BIAS
Fig. 15. RS485-1 three-position slide switch setting BIAS
END
Fig. 16. RS485-1 three-position slide switch setting END
NOTE: All terminals are protected (up to 24 VAC) against
short-circuiting and incorrect wiring – except when
the 3-position slide switch is set to "END," in which
case the terminals of the RS485-1 bus (24, 25,
and 26) have no such protection. Higher voltages
may damage the device.
NOTE: According to BACnet standards, a minimum of one
and a maximum of two BACnet devices must have
its/their bias resistors switched ON. In the case of
the RS485-1 interface of the CIPer Model 50,
25
setting its slide switch to either "BIAS" or "END"
fulfills this requirement.
26
RS485-2 Bias and Termination Resistors
The RS485-2 interface is not affected by the
aforementioned three-position slide switch. The 550Ω bias
resistors and 130Ω termination resistor of the RS485-2 are
thus always ON.
9
+5V
ISO
550 OHM
RS485-1 (+)
RS485-1 (-)
550 OHM
GND-1
+5V
ISO
550 OHM
RS485-1 (+)
150 OHM
RS485-1 (-)
550 OHM
GND-1
31-00233EFS-01
25
26
25
26