Johnson Controls VMA18 Series, Installation Manual

Page: 18 / 26

Table 4: I/O terminal blocks, functions, ratings, requirements, and cables
Terminal block label Terminal labels Function, ratings, and requirements
To determine wire size and
maximum cable length
Analog Output - Voltage Mode (0–10 VDC)
10 VDC maximum output voltage
10 mA maximum output current
External 1k to 50K ohm load required
See Guideline A in Table 5.
OUT n
Binary Output 24 VAC Triac
Connects OUT to OCOM when activated.
External Power Source:
30 VAC maximum voltage to load
0.5 A maximum output current
1.3 A at 25% duty cycle
40 mA minimum load current
See Guideline C in Table 5.
Analog Output Signal Common : All Configurable
Outputs defined as Analog Outputs share a
common, which is isolated from all other commons
except the Binary Input common.
CONFIGURABLE
(Outputs)
OCOM n
Binary Output Signal Common : All Configurable
Outputs defined as Binary Outputs are isolated from
all other commons, including other Configurable
Output commons.
Same as (Configurable) OUT n .
Note: Table 5 defines cable length guidelines
for the various wire sizes that may be used for
input and output wiring.
Table 5: Cable length guidelines for recommended wire sizes
Guideline Wire size/Gauge and type Maximum cable length and type Assumptions
1.0 mm (18 AWG) stranded copper 457 m (1,500 ft) twisted wire
0.8 mm (20 AWG) stranded copper 297 m
(975 ft) twisted wire
297 m (975 ft) twisted wire
0.6 mm (22 AWG) stranded copper 183 m
(600 ft) twisted wire
183 m (600 ft) twisted wire
A
24 AWG stranded copper 107 m (350 ft)
twisted wire
107 m (350 ft) twisted wire
100 mV maximum voltage drop
Depending on the cable length
and the connected input or output
device, you may have to define an
offset in the setup software for the
input or output point.
1.0 mm (18 AWG) stranded copper 229 m (750 ft) twisted wire
0.8 mm (20 AWG) stranded copper 297 m
(975 ft) twisted wire
137 m (450 ft) twisted wire
0.6 mm (22 AWG) stranded copper 183 m
(600 ft) twisted wire
91 m (300 ft) twisted wire
B
24 AWG stranded copper 107 m (350 ft)
twisted wire
61 m (200 ft) twisted wire
100 mV maximum voltage drop
Depending on the cable length
and the connected input or output
device, you may have to define an
offset in the setup software for the
input or output point.
C
See Figure 13 to select wire size/gauge.
Use stranded copper wire.
See Figure 13 to determine cable
length.
Use twisted wire cable.
N/A
Figure 13: Maximum wire length by current and
wire size
VMA1826/1832 VAV Controller Installation Guide 18