National Instruments cFP-PWM-520, FP-PWM-520 User Manual

FIELDPOINT™ OPERATING INSTRUCTIONS
AND SPECIFICATIONS

FP-PWM-520 and
cFP-PWM-520

Eight-Channel, 5 V or 10–30 V PWM Output Module

These operating instructions describe how to install and use
the National Instruments FP-PWM-520 and cFP-PWM-520
pulse-width modulation modules (referred to inclusively as the
[c]FP-PWM-520). For details on configuring and accessing the
[c]FP-PWM-520 over a network, refer to the user manual for the
FieldPoint network module you are using.

Features

The [c]FP-PWM-520 is a FieldPoint pulse-width modulation
(PWM) output module with the following features:

• Eight PWM sourcing output channels

• 0 to 100% duty-cycle capability with 12-bit resolution

• Short-circuit protection for outputs

• Outputs source 5 VDC or 10–30 VDC with user-provided
power supply

• Independent configuration of the output period for each
channel from 1 to 65,535 ms in 1 ms increments

• On/Off LED indicators

• 250 V
verified by 2,300 V

• –40 to 70 °C operation

• Hot swappable

CAT II continuous channel-to-ground isolation,

rms

, 5 s dielectric withstand test

rms

Installing the FP-PWM-520

The FP-PWM-520 mounts on a FieldPoint terminal base
(FP-TB-x), which provides operating power to the module.
Installing the FP-PWM-520 onto a powered terminal base does
not disrupt the operation of the bank.

To install the FP-PWM-520, refer to Figure 1 and complete the
following steps:

1. Slide the terminal base key to either position X, used for any
module, or position 4, used for the FP-PWM-520 module.

2. Align the FP-PWM-520 alignment slots with the guide rails on
the terminal base.

3. Press firmly to seat the FP-PWM-520 on the terminal base.
When the module is firmly seated, the terminal base latch locks
it into place.

4

5

3

6

1

1 I/O Module
2 Terminal Base

FP-PWM-520 and cFP-PWM-520 2 ni.com

3 Alignment Slot
4 Terminal Base Key

Figure 1. Installing the FP-PWM-520

2

5 Latch
6 Guide Rails

Installing the cFP-PWM-520

The cFP-PWM-520 mounts on a Compact FieldPoint backplane
(cFP-BP-x or cFP-180x), which provides operating power to the
module. Installing the cFP-PWM-520 onto a powered backplane
does not disrupt the operation of the bank.

To install the cFP-PWM-520, refer to Figure 2 and complete the
following steps:

1. Align the captive screws on the cFP-PWM-520 with the screw
holes on the backplane. The alignment keys on the
cFP-PWM-520 prevent backward insertion.

2. Press firmly to seat the cFP-PWM-520 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.

3 5

2

2

1

1 cFP I/O Module
2 Captive Screws
3 cFP Controller Module

Figure 2. Installing the cFP-PWM-520

© National Instruments Corp. 3 FP-PWM-520 and cFP-PWM-520

4

4

4 Screw Holes
5 cFP Backplane

Wiring the [c]FP-PWM-520

The FP-TB-x terminal base has connections for each of the eight
output channels and for an external power supply to power the
output channels and field devices. The cFP-CB-x connector block
provides the same connections. Each channel has one output
terminal (V
terminals (COM). All eight channels are referenced to the COM
terminals. The V and V
as are the C and COM terminals.

Table 1 lists the terminal assignments for the signals of each
channel. Terminal assignments are also listed on the side panel
of the cFP-PWM-520 and under the slide-in card on the front of the
FP-PWM-520. Connect to the terminals using the terminal base,
connector block, or other connectivity accessory.

Channel

0 1 17 2, 18

1 3 19 4, 20

2 5 21 6, 22

3 7 23 8, 24

4 9 25 10, 26

5 11 27 12, 28

6 13 29 14, 30

7 15 31 16, 32

*

Install a 1 A maximum, fast-acting fuse on each V

†

Install a 2 A maximum, fast-acting fuse on each V

Use a 5 VDC or 10–30 VDC external power supply for the output
channels. The power supply must provide enough current to power
all of the loads on the output channels, up to a maximum of 1 A per
channel. Connect the external power supply to multiple V and V
terminals and to multiple C and COM terminals as needed to
ensure that the maximum current through any terminal is 2 A
or less.

), one supply terminal (V

OUT

terminals are all internally connected,

SUP

Table 1. Terminal Assignments

Terminal Numbers

*

V

OUT

), and two common

SUP

†

V

SUP

OUT

SUP

COM

terminal.
terminal.

SUP

FP-PWM-520 and cFP-PWM-520 4 ni.com

Install a 2 A maximum, fast-acting fuse between the external
power supply and the V

terminal on each channel. Install

SUP

a 1 A maximum, fast-acting fuse suitable for the load at the
V

terminal. Figure 3 shows fuses where appropriate.

OUT

2 A Max

C V

Protected

Sourcing

Output

[c]FP-PWM-520

V

V

COM

COM

Figure 3. Wiring the [c]FP-PWM-520

User-Supplied

SUP

1 A Max

User-Supplied

Fuse

OUT

Fuse

Load

5 VDC or

+

10–30 VDC

External

–

Power Supply

Caution

Maximum output current for the cFP-PWM-520

is lower than 1 A if the module is operating in the
50–70 °C temperature range. Refer to the Specifications
section for more information, and select fuses for the V

OUT

terminals accordingly.

Pulse-Width Modulator Output Circuit

The [c]FP-PWM-520 output channels are optically isolated from
the rest of the FieldPoint bank. The channels are sourcing outputs
with short-circuit protection circuitry. Sourcing current means that
the V
state of the output period, a transistor is turned on between V
and V
only a small leakage current to flow.

© National Instruments Corp. 5 FP-PWM-520 and cFP-PWM-520

terminal provides a path to a voltage supply. In the ON

OUT

. In the OFF state, this transistor is turned off, allowing

OUT

SUP

In the ON state, the effective resistance between V

OUT

and V

SUP

causes a voltage drop between the external supply voltage and the
output voltage. For example, if the external supply voltage is 5 V
and the output current is 1 A, calculate the output voltage as
follows:

5 V – (1 A × R

where RON is the ON resistance and V

) = V

ON

OUT

is the output voltage.

OUT

Refer to the Specifications section for the value of the ON
resistance.

Short-Circuit Protection

If the protection circuitry detects a short-circuit condition on an
output channel, it disables the output. If the protection circuitry
disables an output that would otherwise be in the ON state, the
status indicator for that channel is still lit, but the output transistor
is turned off.

Detecting a Short-Circuit Condition

To determine whether a channel is in a short-circuit condition,
complete the following steps:

1. In FieldPoint software, set the duty cycle to 100% for the
channel in question. Refer to the Configuring the Output

Channels section for more information about configuring the

duty cycle.

2. Measure the voltage between the V
that channel.

Under normal load conditions, the V
less than 1 V when the output is ON continuously. Any voltage
higher than 1 V indicates a short circuit. Typically, the
V

-to-COM voltage is almost zero if the protection circuitry

OUT

is activated.

OUT

and V

OUT

-to-V

terminals for

SUP

voltage is

SUP

Resetting a Channel in a Short-Circuit Condition

To reset a channel in a short-circuit condition, determine the cause
of the condition and disconnect the load from the channel. The
channel resets automatically when the load is removed.

Alternatively, if completely removing the channel load is not
convenient, reset the channel in any of the following ways:

• In FieldPoint software, set the duty cycle to 0%. The channel
resets immediately.

FP-PWM-520 and cFP-PWM-520 6 ni.com