Campbell Scientific A6REL-12 Relay Driver - Manual (Page 8)

A6REL-12 Relay Driver
4. Installation
The A6REL-12 relay driver includes mounting flanges with keyhole slots that
attach to the backplate of a Campbell Scientific enclosure.
The A6REL-12 must be in an enclosure that provides a pollution degree 2
environment (normally, only nonconductive pollution. However, a temporary
conductivity caused by condensation may be expected). All Campbell Scientific
enclosures meet this requirement.
Table 1 shows the cables recommended for connecting the relays. A two-foot
length sould be sufficient if the datalogger and A6REL-12 are housed in the same
enclosure. Tightening torque should be 4.5 in/lb. A user-supplied cable can be
used if the cable has:
• only copper conductors
• wire range of 26 to 14 AWG
• minimum 60/75 degree C wire
Input power must be connected to a class 2 supply only. All Campbell Scientific
power supplies meet the class 2 supply requirements.
TABLE 1. Recommended Cables to Control Relays
Number of
Relays Controlled
Recommended Cable(s)
1 (1) CABLE3CBL-L
2 (1) CABLE4CBL-L
3 (1) CABLE5CBL-L
4 (2) CABLE3CBL-L
5 (1) CABLE3CBL-L and (1) CABLE4CBL-L
6 (2) CABLE4CBL-L
5. Example Programs
In the following programming examples, temperature is being controlled
between 96
° and 99°F. A copper-constantan thermocouple is measured to
determine the temperature. If the temperature drops below 96 degrees, control
port 1 is set high to activate the associated relay and turn the heater on. If the
temperature equals or exceeds 99
°F, control port 1 is set low to turn the heater
off.
4