National Instruments FieldPoint cFP-RLY-425 User manual

FieldPoint Operating Instructions
cFP-RLY-425
Eight-Channel SPST Relay Module
These operating instructions describe how to install and use the
National Instruments cFP-RLY-425 relay module. For information
about configuring and accessing the cFP-RLY-425 over a network,
refer to the user manual for the FieldPoint network module you are
using.
Features
The cFP-RLY-425 is a Compact FieldPoint relay output module
with the following features:
• Eight single-pole single-throw (SPST) relay channels
• Switches up to 5 A at 18 VDC or 150 VAC, 0.2 A at 125 VDC,
or 3 A at 250 VAC
• –40 to 70 °C operation
• 250 Vrms CAT II continuous channel-to-channel and
channel-to-ground isolation, verified by 2,300 Vrms 1 minute
dielectric withstand test
• Hot swappable
Power Requirement
The cFP-RLY-425 is powered by the FieldPoint network module
through the backplane bus. The cFP-RLY-425 requires up to
1.45 W of power,1which may limit the number of I/O modules that
you can connect to a single network module.
Before you configure a FieldPoint system that uses a cFP-RLY-425
module, calculate the total power consumption of the I/O modules
on the FieldPoint bank. Power requirements are listed in the
Specifications sections of the operating instructions for each
I/O module. The network module user manual lists the maximum
1 1.45 W is the maximum power requirement. Most applications require less power.

cFP-RLY-425 2 ni.com
power that the network module can supply. Make sure the total
power requirement for all of the I/O modules in the bank is less
than the maximum power available from the network module.
Suppose you have a bank with a cFP-2000 network module,
three cFP-RLY-425 modules, and five cFP-DI-300 modules. The
cFP-2000 can supply up to 9 W. The cFP-RLY-425 requires
up to 1.45 W, and the cFP-DI-300 requires 0.185 W. Three
cFP-RLY-425 modules and five cFP-DI-300 modules require a
total of 5.28 W:
3(1.45 W) +5(0.185 W) = 5.28 W
This power requirement is less than the 9 W maximum.
Installing the cFP-RLY-425
The cFP-RLY-425 mounts on a Compact FieldPoint backplane
(cFP-BP-x), which provides operating power to the module.
Installing the cFP-RLY-425 onto a powered backplane does not
disrupt the operation of the bank.
To install the cFP-RLY-425, refer to Figure 1 and complete the
following steps:
1. Align the captive screws on the cFP-RLY-425 with the holes
on the backplane. The alignment keys on the cFP-RLY-425
prevent backward insertion.
2. Press firmly to seat the cFP-RLY-425 on the backplane.
3. Using a number 2 Phillips screwdriver with a shank of at least
64 mm (2.5 in.) length, tighten the captive screws to 1.1 N ⋅m
(10 lb ⋅in.) of torque. The nylon coating on the screws
prevents them from loosening.

© National Instruments Corp. 3 cFP-RLY-425
Figure 1. Installing the cFP-RLY-425
Mounting the System Upright
To ensure maximum cooling efficiency, mount the Compact
FieldPoint system so that the I/O module vents are at the top and
bottom as shown in Figure 2.
1 cFP-RLY-425
2 Captive Screws
3 cFP Controller Module
4 Screw Holes
5 cFP Backplane
2
2
1
3 5
4
4

cFP-RLY-425 4 ni.com
Figure 2. Mounting the System Upright
Wiring the cFP-RLY-425
Each relay channel of the cFP-RLY-425 has two terminals, CHx
and COMx.
Caution Ensure that hazardous voltage wiring is
performed only by qualified personnel adhering to local
electrical standards. A hazardous voltage is a voltage
greater than 42.4 Vpeak or 60 VDC.
The screw terminals for the CHxand COMxpins are on two
detachable screw-terminal connectors. Table 1 lists the terminal
assignments for the signals of each channel.
Table 1. Terminal Assignments
Channel
Terminal Numbers
CHxCOMx
0L1 L3
1L5 L7
2L9 L11
3L13 L15
4R15 R13
5R11 R9
6R7 R5
7R3 R1
Up

© National Instruments Corp. 5 cFP-RLY-425
Note that screw terminals 1–15 on the left connector are for
channels 0–4, and screw terminals 15–1 on the right connector are
for channels 4–7. Figure 3 shows how to orient the two connectors
with respect to the cFP-RLY-425.
Figure 3. cFP-RLY-425 Screw-Terminal Connectors
78563412 1513 1411 12910
78563412 1513 1411 12910
Compact FieldPoint
POWER
READY
CH0
COM0
CH1
COM1
CH2
COM2
CH3
COM3
CH4
COM4
CH5
COM5
CH6
COM6
CH7
COM7
cFP-RLY-425

cFP-RLY-425 6 ni.com
Wire the screw terminals and place the connector in the shell as
shown in Figure 4. Make sure that you use the half of the shell with
the strain-relief screw holes.
Figure 4. Placing the Screw-Terminal Connector in the Shell
Install the strain-relief bar as shown in Figure 5.
Figure 5. Installing the Strain-Relief Bar on the Connector Shell

© National Instruments Corp. 7 cFP-RLY-425
Close the shell as shown in Figure 6.
Figure 6. Closing the Connector Shell
Install the labels and label covers as shown in Figure 7.
Figure 7. Installing the Label Covers on the Connector

cFP-RLY-425 8 ni.com
Insert the connector into the cFP-RLY-425 as shown in Figure 8,
then tighten both flange screws on the connector.
Figure 8. Installing One Assembled Screw-Terminal Connector
Connecting Loads to the cFP-RLY-425
Wire a load to a channel of the cFP-RLY-425 as shown in Figure 9.
Install a 5 A, 250 V maximum, fast-acting fuse (F 5 A L 250V) at
the COMxterminal to protect the module and the load from
damage.
Figure 9. Connecting a Load to One Channel of the cFP-RLY-425
Compact FieldPoint
POWER
READY
CH0
COM0
CH1
COM1
CH2
COM2
CH3
COM3
CH4
COM4
CH5
COM5
CH6
COM6
CH7
COM7
cFP-RL
Y-425
+
–
cFP-RLY-425
COM
x
CH x
or
AC
Load
5 A,
250 V max

© National Instruments Corp. 9 cFP-RLY-425
The cFP-RLY-425 has eight SPST (single-pole single-throw)
electromechanical relays. The power-up state is OFF (open) to
ensure safe installation. In the ON state, the CHxand COMxrelay
contacts connect to form a short circuit. In the ON state, there is an
effective resistance of up to 50 mΩbetween the CHxand COMx
terminals, which causes a voltage drop.1For example, if the current
is 5 A, the voltage drop across the CHxand COMxterminals can
be as high as 0.25 V.
The amount of current the relay can switch depends on the voltage,
the type of load, and the ambient temperature. Refer to the
Specifications section for more information.
Protecting Contacts for Inductive Loads
When inductive loads are connected to the relays, a large
counter-electromotive force may occur at relay switching time
because of the energy stored in the inductive load. These flyback
voltages can severely damage the relay contacts and greatly
shorten the life of the relay.
It is best to limit flyback voltages by installing a flyback diode
across an inductive DC load or a metal oxide varistor (MOV)
across an inductive AC load.
In addition, the cFP-RLY-425 has internal protection MOVs to
prevent excessively high voltage from being applied across the
contacts. The MOVs are located between the CHxand COMx
contacts of each relay. However, National Instruments
recommends the use of a protection circuit across each inductive
load. The flyback protection causes a small leakage current, which
is detailed in the Specifications section.
Refer to the NI Switches Help for information about selecting and
installing contact protection circuits. Go to ni.com/manuals and
select Current Manual Revisions»Switches»Software»
NI Switches Help.
Status Indicators
After you install the cFP-RLY-425 onto a backplane and apply
power to the network module, the green POWER indicator lights
and the cFP-RLY-425 informs the network module of its presence.
When the network module recognizes the cFP-RLY-425, it sends
1 At the end of relay life, the path resistance rises rapidly above 1 Ω.

cFP-RLY-425 10 ni.com
initial configuration information to the cFP-RLY-425. After the
cFP-RLY-425 receives this initial information, the green READY
indicator lights and the module is in normal operating mode.
Isolation and Safety Guidelines
Caution Read the following information before
attempting to connect the cFP-RLY-425 to any circuits
that may contain hazardous voltages.
This section describes the isolation of the cFP-RLY-425 and its
compliance with international safety standards. The field wiring
connections are isolated from the backplane and the inter-module
communication bus. The isolation barriers in the module provide
250 Vrms Measurement Category II continuous isolation, verified
by 2,300 Vrms, 1 minute dielectric withstand test. The
cFP-RLY-425 provides double insulation (compliant with
IEC 61010-1) for working voltages of 250 Vrms1. Safety standards
(such as those published by UL and IEC) require the use of double
insulation between hazardous voltages and any human-accessible
parts or circuits.
Never try to use any isolation product between human-accessible
parts (such as DIN rails or monitoring stations) and circuits that
can be at hazardous potentials under normal conditions, unless the
product is specifically designed for such an application, as is the
cFP-RLY-425.
Even though the cFP-RLY-425 is designed to handle applications
with hazardous potentials, follow these guidelines to ensure a safe
system:
• You must connect the protective earth (PE) ground terminal on
the cFP-BP-xbackplane to the system safety ground. The
backplane PE ground terminal has the following symbol
stamped beside it: . Connect the backplane PE ground
terminal to the system safety ground using 14 AWG (1.6 mm)
wire with a ring lug. Use the 5/16 in. panhead screw shipped
with the backplane to secure the ring lug to the backplane PE
ground terminal.
1 Working voltage is defined as the signal voltage plus the common-mode voltage.
Common-mode voltage is the voltage of the module with respect to ground.