Campbell Scientific A6REL-12 User Manual

A6REL-12 Relay Driver

Revision: 7/09

Copyright © 1985-2009

Campbell Scientific, Inc.

Warranty and Assistance

The A6REL-12 RELAY DRIVER is warranted by CAMPBELL
SCIENTIFIC, INC. to be free from defects in materials and workmanship
under normal use and service for twelve (12) months from date of shipment
unless specified otherwise. Batteries have no warranty. CAMPBELL
SCIENTIFIC, INC.'s obligation under this warranty is limited to repairing or
replacing (at CAMPBELL SCIENTIFIC, INC.'s option) defective products.
The customer shall assume all costs of removing, reinstalling, and shipping
defective products to CAMPBELL SCIENTIFIC, INC. CAMPBELL
SCIENTIFIC, INC. will return such products by surface carrier prepaid. This
warranty shall not apply to any CAMPBELL SCIENTIFIC, INC. products
which have been subjected to modification, misuse, neglect, accidents of
nature, or shipping damage. This warranty is in lieu of all other warranties,
expressed or implied, including warranties of merchantability or fitness for a
particular purpose. CAMPBELL SCIENTIFIC, INC. is not liable for special,
indirect, incidental, or consequential damages.

Products may not be returned without prior authorization. The following
contact information is for US and International customers residing in countries
served by Campbell Scientific, Inc. directly. Affiliate companies handle
repairs for customers within their territories. Please visit
www.campbellsci.com to determine which Campbell Scientific company
serves your country.

To obtain a Returned Materials Authorization (RMA), contact CAMPBELL
SCIENTIFIC, INC., phone [phone]. After an applications engineer
determines the nature of the problem, an RMA number will be issued. Please
write this number clearly on the outside of the shipping container.
CAMPBELL SCIENTIFIC's shipping address is:

CAMPBELL SCIENTIFIC, INC.

RMA#_____
815 West 1800 North
Logan, Utah 84321-1784

For all returns, the customer must fill out a “Declaration of Hazardous Material
and Decontamination” form and comply with the requirements specified in it.
The form is available from our website at
completed form must be either emailed to [e-mail]
435-750-9579. Campbell Scientific will not process any returns until we
receive this form. If the form is not received within three days of product
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customer’s expense. Campbell Scientific reserves the right to refuse service on
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concerns for our employees.

www.campbellsci.com/repair

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or faxed to

A6REL-12 Table of Contents

PDF viewers note: These page numbers refer to the printed version of this document. Use
the Adobe Acrobat® bookmarks tab for links to specific sections.

1. Function........................................................................1

2. Specifications ..............................................................3

3. Powering the A6REL-12 ..............................................3

4. Installation....................................................................4

5. Example Programs......................................................4

5.1 CRBasic....................................................................................................5

5.2 EDLOG.....................................................................................................6

Figures

Table

1. A6REL-12 Panel View...............................................................................1

2. Position of Contacts When Coil IS Energized (ON) ..................................2

3. Position of Contacts When Coil IS NOT Energized (OFF)........................2

1. Recommended Cables to Control Relays ...................................................4

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A6REL-12 Relay Driver

1. Function

The A6REL-12 (Figure 1) drives six dual single pole double throw internal
relays for control of up to 12 external AC or DC devices. Each of the six
relays has a three position toggle switch; "on" and "off" for manual override,
and "auto" for datalogger control. In the on position, the common and
normally open contacts are shorted (Figures 2 and 3). In the auto position, the
state of a relay is controlled by a datalogger control port.

Please note that the A6REL-12 is not compatible with our CR200-series
dataloggers.

FIGURE 1. A6REL-12 Panel View

1

A6REL-12 Relay Driver

FIGURE 2. Position of Contacts When Coil IS Energized (ON)

FIGURE 3. Position of Contacts When Coil IS NOT Energized (OFF)

2

2. Specifications

Operating voltage: 12 VDC nominal (8.4 to 24)
Current drain at 12 VDC: 6 μa quiescent; 30 mA per active LED

Toggle Switch: ON/OFF manual override; AUTO for

Underwriters Laboratories (UL) and Canadian Underwriters Laboratories
(CUL) listed product. UL and CUL listing number is 5Z21.

RELAY SPECIFICATIONS

Arrangement: Dual single pole double throw Break

Contact material: Gold-clad silver
Individual contact rating: 2A at 30 VDC

Coil voltage: 8.4 to 24 VDC
Coil resistance: 720 Ohms ±10%

A6REL-12 Relay Driver

(switch ON or AUTO active).

datalogger control.

before make

0.6A at 125 VAC

Expected life (contact closures):
Mechanical 10
Electrical 2A at 30 VDC 5x10
1A at 30 VDC 2x10

Actuation/release time: Approx. 3 ms
Operating temperature: -40° to 70°C

NOTE

The A6REL-12 protects each contact against voltage surges of
180 VDC (130 V rms) or greater with a power content of 8
Watts maximum and maximum duration of 0.1 ms.

3. Powering the A6REL-12

The A6REL-12 may be powered by the datalogger power supply or a separate

8.4 to 24 VDC battery.

If the 21X power supply is used to power the A6REL-12, all low level analog
measurements (thermocouples, pyranometers, thermopiles, etc.) must be made
differentially. This is a result of slight ground potentials created along the 21X
analog terminal strip when the 12 volt supply is used to power peripherals.
This limitation reduces the number of available analog channels and may
require the use of a separate battery to power the A6REL-12.

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5
6

3

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

5.1 CRBasic

Although the following example is a CR1000 program, other dataloggers that
use CRBasic such as the CR800 and CR3000 are programmed similarly.

'CR1000 Series Datalogger

'Declare Public Variables

Public PTemp, batt_volt, P, TC

'Define Data Tables

DataTable (Test,1,-1)
DataInterval (0,15,Sec,10)
Minimum (1,batt_volt,FP2,0,False)
Sample (1,PTemp,FP2)
Sample (1,TC,FP2)

EndTable

'Main Program

BeginProg
Scan (5,Sec,0,0)
Battery (Batt_volt)

'Measure TC reference temperature

PanelTemp (PTemp,250)

'Make temperature measurement and convert it to degrees Fahrenheit

TCDiff (TC,1,mV2_5C,1,TypeT,PTemp,True ,0,250,1.8,32)

'If temperature is greater than 99 set Port low

If TC>99 then
P=0

'If temperature is less than 96 set Port high

ElseIf TC<96 then
P=1
EndIf
PortSet (1 ,P)

'Call Output Tables
'Example:

CallTable Test
NextScan
EndProg

A6REL-12 Relay Driver

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A6REL-12 Relay Driver

5.2 EDLOG

*1 Table 1 Program
01: 5 Sec. Execution Interval

1: Panel Temperature (P17) Measure the TC
1: 1 Loc [:REF TEMP ] reference temperature

2: Thermocouple Temp (DIFF) (P14)
1: 1 Rep Measure
2: 1 5 mV slow Range temperature
3: 1 IN Chan
4: 1 Type T (Copper-Constantan)
5: 1 Ref Temp Loc REF TEMP
6: 2 Loc [:TEMP ]
7: 1.8 Mult
8: 32 Offset

3: If X<=>F (P89) If temp is greater
1: 2 X Loc TEMP than or equal to
2: 3 >= 99, set Flag 1 low
3: 99 F
4: 21 Reset flag 1

4: If X<=>F (P89) If temp is less
1: 2 X Loc TEMP than 96, set
2: 4 < Flag 1 high
3: 96 F
4: 11 Set flag 1

5: Set Port (P20) Set Port 1
1: 11 Set according to flag 1 according to
2: 1 Port Number Flag 1

Input Location Labels:

1:REF TEMP 2:TEMP

Although the following example is a 21X program, other dataloggers that use
Edlog such as the CR10(X) and CR23X are programmed similarly.

6

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