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The OP8930 is a 16-channel analog input or output board with fault insertion, compatible with the NI SLSC-12001 Platform.

Features

• Analog signal conditioning & FIU on a single board

• 16 channels on two 8-channel OP8Gxx modules 

• Ain and Aout user-configurable conditioning circuit

• Fault insertions module FIU as an option

Board Architecture

The board features two groups of 8 channels and a set of relays adding fault insertion capability for each signal.
The general layout of the board is as follows, with the front Interface connectors on the left and the SLSC backplane connectors on the right: 

Open

The input/output conditioning is managed by a combination of these two OP8Gxx (also called Type-G) modules: 

• OP8G01: 8-channel analog Input conditioning module

• OP8G03: 8-channel analog Output conditioning module

A CPLD is used to configure the fault insertion unit (FIU) section and the OP8G01 and OP8G03 modules.  It is responsible for the communication of the SLSC card within the NI environment for identification, error reporting, etc. It also receives configuration from the software and applies it to the FIU and to some of the I/Os.

The FIU specification and topology are common to all OP8900 boards.

Channels Description

Analog Inputs

Conditioning Circuit Configuration

The conditioning circuit is user-configurable by using passive components on through-hole sockets. Each channel is configurable independently. This feature allows adapting the module for: 

• Custom impedance matching

• Custom analog filter

• Custom analog divider

The configurable elements consist of a set of three resistors (R_A, R_B, R_C) and two capacitors (C_A, C_B) as shown below:

Open

By default, R_C, C_A and C_B are not installed, and R_A and R_B are 0 Ohm.

Use the table below to locate these elements on the board:

Analog Outputs

The OP8G03 module (P/N 126-0642) condition ±10V single-ended analog signals coming from the PXI chassis into ±20V differential analog output signals (OP8934/OP8935) or ±10V differential analog output signals (OP8931/OP8933) to be connected to the unit under test.

The maximum current per channel is ±50mA continuous, for a maximum of 250 mA per OP8930 board.

Conditioning Circuit Configuration

The conditioning circuit is user-configurable by using passive components on through-hole sockets. Each channel is configurable independently.
This feature allows adapting the module for: 

• Custom impedance matching

• Custom analog filter

• Custom analog divider

The configurable elements consist of a set of three resistors (R_A, R_B, R_C) and two capacitors (C_A, C_B) as shown below:

Open

By default, C_A and C_B are not installed, and R_A, R_B and R_C are 10 Ohm.

Use the table below to locate these elements on the board:

For PCB Rev 2.0, C_A is aligned with R_A, C_B is aligned with R_B and R_C is between C_A and C_B

Channels Calibration

For both analog inputs and analog outputs, there is no internal calibration on the SLSC card. Through NI VeriStand or manually in the model, it is possible to include m x + b coefficients to compensate the errors and variation of the components on the cards. OPAL-RT TECHNOLOGIES Inc. do not provide the compensation coefficients. In the OP8930 specification page, the exact function transfer is provided with the maximum expected gain error. Based on the required level of precision, the nominal coefficients can be used. If a better precision is required to correct all errors including cabling and setup, here a quick calibration procedure:

Analog Inputs Manual Calibration

Required equipment:

• Voltage source

• Calibrated precision voltmeter

• Simulator

• SLSC Chassis with OP893x

Procedure:

1. Connect a voltage source to all analog inputs and the voltmeter in parallel;

2. Measure the voltage of the source with the voltmeter;

3. In the simulation, measure the voltage on every channel

4. Repeat steps 2 and 3 for few different voltages spread on the usable range, recommended minimum 3 voltage values;

5. Calculate a linear regression between the source given by the voltmeter and voltage measure in the model for every channel;

6. Include the coefficients calculated in step 5 into the model or built-in NI VeriStand calibration function.

Analog Outputs Manual Calibration

Required equipment:

• Calibrated precision voltmeter

• Simulator

• SLSC Chassis with OP893x

Procedure:

1. From a basic simulation, output a DC voltage on every channel;

2. Measure the voltage at the output of the SLSC card for every channel;

3. Repeat steps 1 and 2 for few different voltages spread on the usable range, recommended minimum 3 voltage values;

4. Calculate a linear regression between the voltage of the simulation and voltage measure in voltmeter for every channel;

5. Include the coefficients calculated in step 4 into the model or built-in NI VeriStand calibration function.

OP8930 Configurations

Several assemblies of the OP8930 are available, as listed below, with different counts of inputs and outputs, and with or without the FIU section populated.