VXI VT1508A User Manual

bus

Eight-Channel
Fixed Filter and Amplifier
Signal Conditioning Plug-on
VT1508A

User’s Manual

The VT1508A manual also applies to Agilent/HP E1413Bs as Agilent/HP E1413 Option 18.

Enclosed is the User’s Manual for the VT1508A Signal Conditioning Plug-on. Insert this
manual in your VT1413C or Agilent/HP E1313 manual behind the “Signal Conditioning
Plug-ons” divider.

Copyright © VXI Technology, Inc., 2003

Manual Part Number: 82-0082-000 Printed: July 9, 2003

Printed in U.S.A.

Eight-Channel Fixed Filter and Amplifier

Introduction

The VT1508A is a Signal Conditioning Plug-on that provides eight fixed low-pass
filters with a 3 dB cutoff frequency of 7 Hz and eight amplifiers with gain of 16.
Also provided is input over-voltage protection and open transducer detection on
each channel.

About this Manual

This manual shows you how to control the Signal Conditioning Plug-on (SCP)
using SCPI commands as well as Register-Based commands, and explains the
capabilities of this SCP. Finally, it covers specifications for this SCP. The contents
of this manual are:

VT1508A

Signal Conditioning Plug-on

·

Installation .................................................... 3

·

Identifying the Plug-on ..........................................3

·

Connecting To The Terminal Module................................ 4

·

Programming With SCPI Commands ...............................6

·

Programming With Register Commands .............................8

·

Specifications ................................................. 10

Installation

Installation for this Plug-onis commonto several others and is covered inChapters

1 and 2 of your VT1413C or Agilent/HP E1313 manual.

Identifying the Plug-on

You’ll find the VXI Technology part number on the connector side of the SCP to
the left of the serial number bar code. For the VT1508A, the part number is :
VT1508A.

Introduction VT1508A Fixed Filter+Amplifier SCP 3

Connecting To The Terminal Module

This section shows how to make connections to the Terminal Module.

The SCP connections for the Terminal Modules are shown on the stick-on labels
that came with the SCP. Use the appropriate label for the type of Terminal Module
you have. The connections and appropriate stickers are as follows:

For VT1413C and above Terminal Modules, use stickers for VT1508A SCPs.

·

The connections are shown in Figure 1.

For Agilent/HP E1313 Terminal Moduless, use stickers for VT1508A SCPs.

·

The connections are shown in Figures 2 and 3.

For Agilent/HP E1413B and below Terminal Modules, use stickers for

·

Agilent/HP E1413 Option 18 SCPs. The connections are shown in Figure 4.

Figure 1 VT1508A C-Size Terminal Module Connections

4 VT1508A Fixed Filter+Amplifier SCP Connecting To The Terminal Module

Figure 2 VT1508A B-size Terminal Module Connections (Ch 00-31)

Figure 3 VT1508A B-size Terminal Module Connections (Ch 32-63)

Figure 4 Agilent/HP E1413B Option 18 Terminal Module Connections

Connecting To The Terminal Module VT1508A Fixed Filter+Amplifier SCP 5

Programming With SCPI Commands

The SCPI commands shown here are covered inChapters3and 5 of your VT1413C
or Agilent/HP E1313 manual. This section will relate those commands to the
parameter values which are specific to this Plug-on.

Checking the ID

of the SCP

Querying the Filter

Cutoff Frequency

To verify the SCP type(s) installed on the VT1413C or Agilent/HP E1313 use the
SYSTem:CTYPe? (@<channel>) command.

The channel parameter specifies a single channel in the channel range

·

covered by the SCP of interest. The first channel number for each of the eight
SCP positions are; 0,8,16,24,32,40,48 and 56.

The value returned for the SCP in an Agilent/HP E1413B is:

HEWLETT-PACKARD,E1413 Opt 18 8-Channel Fixed Gain-Filter SCP,0,0

The value returned for the SCP in a VT1413C or Agilent/HP E1313A is:

HEWLETT-PACKARD,E1508 8-Channel Fixed Gain-Filter SCP,0,0

To determine the type of SCP installed on channels 0 through 7 send

SYST:CTYP? (@100)

enter statement here

While the VT1508A does not provide programmable cutoff frequency the filter
frequency can be queried. Theresponse to this query will always be 7. To query any
channel for its cutoff frequency use the INPut:FILTer[:LPASs]:FREQuency?
(@<channel>) command. The INP:FILT:FREQ? command returns the numeric
cutoff value currently set for the channel specified.

query SCP type @ ch 0

·

The channel parameter must specify a single channel.

To query the cutoff frequency of channel 6 send

INP:FILT:FREQ? (@106)

enter statement here

Querying the

Filter State

6 VT1508A Fixed Filter+Amplifier SCP Programming With SCPI Commands

While the VT1508A does not allow controlling whether the filters are enabled or
disabled, this state can be queried. The response to this query will always be 1. To
query any channel to determine if it is enabled or disabled use the
INPut:FILTer[:LPASs][:STATe]? (@<channel>) command. The INP:FILT?
command returnsa0ifthechannel is OFF ora1ifthechannel is ON.

query channel 6

The channel parameter must specify a single channel.

·

To query the filter state of channel 2 send

Querying the

Channel Gain

Detecting Open

Transducers

INP:FILT? (@102)

enter statement here

While the VT1508A’s amplifiers have fixed gain, the channel gain can be queried.
The response to this query willalways be 16. To query any channel to determineits
gain setting use the INPut:GAIN? (@<channel>) command. The INP:GAIN?
command returns the current gain value for the specified channel.

The channel parameter must specify a single channel.

·

To query the gain setting of channel 8 send

INP:GAIN? (@108)

enter statement here

This SCP provides a method to detect open transducers. When Open Transducer
Detect (OTD) is enabled, the SCP injects a small current into the HIGH and LOW
input of each channel.The polarityof the current pulls the HIGH inputs toward +17
volts and the LOW inputs towards -17 volts. If a transducer is open, measuring that
channel will return anover-voltage condition. OTD is available on a per SCP basic.
all eight channels of an SCP are enabled or disabled together. See Figure for a
simplified schematic diagram of the OTD circuit.

query channel 2

query channel 8

Signal Input

High

Low

Figure 5 Open Transducer Detect Circuit

Signal Conditioning Plug-on

100M

100M

Multiplexer

High

+17V

3K

Gnd.

3K

-17V

Low

Programming With SCPI Commands VT1508A Fixed Filter+Amplifier SCP 7

NOTES 1) When OTD is enabled, the inputs have up to 0.2 µA injected into them. If this

current will adversely affect your measurement, but you still want to check for open
transducers, you can enable OTD, make a single scan, check the CVT for bad
measurements, then disable OTD and make your regular measurement scans. The
specifications apply only when OTD is off.

2) Allow 5 minutes before checking for open transducers to allow filter capacitors
to charge.

To enable or disable Open Transducer Detection, use the DIAGnostic:OTDetect
<enable>, (@<ch_list>) command.

The enable parameter can specify ON or OFF

·

An SCP is addressed when the ch_list parameter specifies a channel number

·

contained on the SCP. The first channel on each SCP is:

0, 8, 16, 24, 32, 40, 48, and 56

To enable Open Transducer Detection on all channels on SCPs 1 and 3:

DIAG:OTD ON, (@100,116)

To disable Open Transducer Detection on all channels on SCPs 1 and 3:

DIAG:OTD OFF, (@100,116)

Register Based Programming

The register-based commands shown here are covered in Appendix D of the
VT1413C or Agilent/HP E1313 manual. You should read that section first to
become familiar with accessing registers and executing Register-Based
Commands. This section will relate those commandsto theparameter valueswhich
are specific to this Plug-on.

When Register Programming an SCP most communication is through the Signal
Conditioning Bus. For that you will use the Register Commands:

SCBWRITE <regaddr><regvalue>

and

SCBREAD? <regaddr>

0 is on SCP 1 and 16 is on SCP3

8 VT1508A Fixed Filter+Amplifier SCP Register Based Programming

VT1508A Register Map

Read (returned value) Write( <regvalue>) SCP Register <regaddr> Value

SCP ID (901016)

Whole SCP Reg 0 00ppp000000

ppp=Plug-on
ccc=SCP channel

In addition you will access bits in the Card Control register to control Open
Transducer Detection.

Checking ID of SCP To query an SCP for its ID value, write the following value to Parameter Register 1:

()SCP number ´ 40
Then write the opcode for SCBREAD? (080016) to the Command Register. The ID
value will be returned to the Query Response Register.

16

2

Detecting Open

Transducers

15 14 14-13 12 11 10-8 7-0

PSI Pwr Reset FIFO Mode unused FIFO Clear VPPEN A24 Window Open Transducer Detect

Open Transducer Detection (OTD) is controlled by bits in the Card Control
Register. For more information on OTD see Figure 1.

Card Control Register (Base + 12

)

16

Writing aone (1) to abit enables open transducer detect on that signal conditioning
module. Writing a zero (0) to a bit disables open transducer detect.

Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0

SCP 7 SCP 6 SCP 5 SCP 4 SCP 3 SCP 2 SCP 1 SCP 0

Register Based Programming VT1508A Fixed Filter+Amplifier SCP 9

Specifications

These specifications for the VT1508A reflect the combined performance of the
VT1413C or Agilent/HP E1313 and the VT1508A Signal Conditioning Plug-on.
These specifications are not to be added to those presented in the VT1413C User’s
Manual.

General Specifications

Measurement ranges

DC Volts ±3.9 mV to ±1 V FS

Temperature Thermocouples - -200 to +1700°C

Resistance (Opt 15 required) 128 Ohms to 131 kOhms FS

Strain 25,000 µe or limit of linear range of strain gage

Maximum input voltage

(Normal mode plus common mode)

Maximum common mode

Thermistors - (Opt 15 required) -80 to +160°C
RTD’s - (Opt 15 required) -200 to +850°C

Operating: <±16 V peak Damage level: > ±42 V peak

Operating: <±16 V peak Damage level: > ±42 V peak

voltage

Normal mode rejection

Common mode rejection

Input impedance

100 MOhm ±10% (each differential input to ground)

@ 7 Hz -3 dB, @ 60 Hz >-25 dB

0 - 60 Hz -100 dB

Maximum tare cal offset

10 VT1508A Fixed Filter+Amplifier SCP Specifications

(Maximum tare offset depends on A/D range and SCP gain)

A/D range

±V F.Scale

Max Offset 0.20009 0.05007 0.01317 0.00349 0.00112

16 4 1 0.25 0.0625

Measurement accuracy
DC Volts

(90 days) 23°C±1°C (with *CAL? done after 1 hr warm up and CAL:ZERO? within 5
min.). If autoranging is ON, add ±0.02% FS to accuracy specifications.

For Agilent/HP E1313, multiply Noise Spec. by 1.4.

Temperature Coefficients:

Measurement accuracy
Temperature

(simplified specifications, see
temperature accuracy graphs in
VT1413C manual for details)

Thermocouples

Gain 16

Type E

Range
±VFS

.0039
.0156
.0625

.25

1

* [SENSe:]FILTer[:LPASs][:STATe] ON (max scan rate - 100 rdgs/sec/channel)

Gain - 15 ppm/°C. Offset - (0 - 30°C) 0.16 µV/°C, (30 - 40°C) 0.18 µV/°C,

Linearity

% of reading

0.01

0.01

0.01

0.01

0.01

(40-55°C) 0.39 µV

Offset Error

mV (10Hz)

3.8

4.2

4.9
8

31

Noise mV

3 sigma

3.4

4.4

7.5
28

113

Noise mV*

3 sigma

2.9

3.8

6.3
23
64

(90 days) 23°C±1°C (with *CAL? done after 1 hr warm up and CAL:ZERO? within 5
min.). If autoranging is ON, add ±0.02% FS to accuracy specifications.

The temperature accuracy specifications include instrument and firmware linearization
errors. The linearization algorithm used is based on the IPTS-68(78) standard transducer
curves. Add your transducer accuracy to determine total measurement error.

A/D Filter

OFF

-200 to 0°C 0 to 200°C 200 to 400°C 400 to 800°C

1.30°C 0.14°C 0.14°C 0.20°C

Type EEXtended

Type J

Type K

Type R

A/D Filter

OFF

A/D Filter

OFF

A/D Filter

OFF

A/D Filter

OFF

-200 to 0°C 0 to 200°C 200 to 800°C 800 to 1000°C

1.80°C 0.30°C 0.20°C 0.35°C

-200 to 0°C 0 to 280°C 280 to 600°C 600 to 775°C

1.60°C 0.15°C 0.22°C 0.22°C

-200 to 0°C 0 to 375°C 375 to 800°C 800 to 1400°C

2.50°C 0.20°C 0.25°C 0.40°C

0 to 100°C 100 to 200°C 200 to 600°C 600 to 1000°C

1.80°C 0.90°C 0.70°C 0.60°C

[SENSe:]FILTer[:LPASs][:STATe] ON (max scan rate - 100 rdgs/sec/channel)

Specifications VT1508A Fixed Filter+Amplifier SCP 11

Measurement accuracy
Temperature (cont.)

Thermocouples (cont.)

(simplified specifications, see temperature accuracy graphs in VT1413C manual for details)

Type S

Type T

5kW Reference Thermistor

100 W Reference RTD

100 W RTD

A/D Filter

OFF

A/D Filter

OFF

A/D Filter

A/D Filter

A/D Filter

0 to 100°C 100 to 200°C 200 to 800°C 800 to 1750°C

3.50°C 1.75°C 0.80°C 0.85°C

-200 to -100°C -100 to 0°C 0 to 200°C 200 to 400°C

1.55°C 0.32°C 0.18°C 0.18°C

-10 to 65°C 65 to 85°C

OFF

OFF

OFF

0.012°C 0.013°C

-125 to 70°C

0.145°C

-200 to 75°C 75 to 300°C 300 to 600°C 600 to 970°C

0.08°C 0.21°C 0.27°C 0.37°C

2252 W Thermistor

5kW Thermistor

10 kW Thermistor

A/D Filter

OFF

A/D Filter

OFF

A/D Filter

OFF

0 to 30°C 30 to 70°C 70 to 80°C 80 to 100°C

0.006°C 0.013°C 0.010°C 0.014°C

0 to 30°C 30 to 70°C 70 to 85°C

0.012°C 0.014°C 0.019°C

0 to 30°C 30 to 60°C 60 to 90°C 90 to 115°C

0.015°C 0.016°C 0.018°C 0.022°C

12 VT1508A Fixed Filter+Amplifier SCP Specifications