Honeywell SV2 Series Installation Instructions Manual page 5

3
Battery
1. Remove the BATTERY compartment cover on back of the
display. Refer to Fig. 5.
2. A CR2032 coin battery is provided in the bag assembly
included in the HMI shipping box. Install the battery in the
slot, observing the polarity. Refer to Fig. 6.
3. Replace battery compartment cover.
4
Valve Modbus Bias Setup
The SV2 Series valve can communicate via Modbus RTU communication with any compatible device. Only RTU communications
with 1 start bit, 8 data bits, 1 stop bit and no parity is supported.
When more than one SV2 Series valve is connected to the HMI or PC Tools or directly connected to a building automation
system, the Modbus termination and bias resistors should be adjusted appropriately. The resistors can be found inside the
electrical enclosure on the right-hand side and are present in all intelligent valves models; valves where the 9th digit in the part
number string are 6, 7, 8 or 9. Refer to Fig. 7.
The TERMIN. (termination) resistor in the ON position helps to improve signal integrity for the best performance in regards to
EMC (electromagnetic compatibility). The termination resistor may be especially helpful to improve communication when the
SV2 Series connected valve is at the end of the communication BUS.
The BIAS resistors in the ON position provide differential resistance for some older communication systems where
communication can be lost with zero voltage present on the BUS. Resistors 1 and 3 should always be in the OFF or ON positions
together. Refer to Table. 2.
Note: If communication is problematic with all daisy-chained valves connected to the master control, adjusting the two BIAS
resistors may solve the issue.
MODBUS
OFF
BIAS
TERMIN.
BIAS
Fig. 7. SV2 Series valve Modbus bias
and termination resistors.
SV2 Series Valve Programming Tool
HMITOOL-000
Table 2. Modbus bias resistor setup.
SV2 Series Valve
Not at
BUS end
X
ON
X
1
2
3
M35527
Fig. 5. Battery compartment.
Differential Biasing
Not
At BUS end required
X
X X
X
5
Fig. 6. Install CR2032 coin battery.
Required OFF
X
BIAS
X
TERMIN.
BIAS X
BIAS
X
X
TERMIN.
BIAS
X
BIAS
TERMIN.
X
BIAS
BIAS
X
TERMIN.
BIAS
ON
1
2
3
X
1
2
X
3
1
X 2
3
X
1
X
2
X 3