Measurement CIO-SSH16 User Manual

CIO-SSH16

USER’S MANUAL

Revision 3

October, 2000

MEGA-FIFO, the CIO prefix to data acquisition board model numbers, the PCM prefix to data
acquisition board model numbers, PCM-DAS08, PCM-D24C3, PCM-DAC02, PCM-COM422,
PCM-COM485, PCM-DMM, PCM-DAS16D/12, PCM-DAS16S/12, PCM-DAS16D/16,
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(C) Copyright 2000

HM CIO-SSH16.lwp

Measurement Computing Corp.

1.0 SOFTWARE INSTALLATION .....................................

2.0 HARDWARE INSTALLATION ..................................

3.0 SIGNAL CONNECTION ..........................................

4.0 ARCHITECTURE ................................................

5.0 SPECIFICATIONS ..............................................

6.0 ANALOG ELECTRONICS .......................................

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12.1 INTRODUCTION ..............................................

22.2 POWER CABLE ...............................................

32.3 SIGNAL CABLE ...............................................

42.4 ANALOG INPUT BOARD SETUP .................................

42.5 GAIN SWITCHES ..............................................

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53.1 CONNECTOR DIAGRAM .......................................

53.2 ANALOG INPUTS .............................................

53.3 FLOATING DIFFERENTIAL .....................................

63.4 DIFFERENTIAL ...............................................

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84.1 ANALOG INPUT ...............................................

84.2 AMPLIFICATION ..............................................

94.3 CIO-SSH16 vs. PROGRAMMABLE GAIN A/D BOARDS ..............

104.4 SAMPLE & HOLD ............................................

124.5 DROOP RATE ................................................

134.6 ADDING AMPLIFIERS & SAMPLE / HOLD CHIPS .................

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166.1 VOLTAGE DIVIDERS .........................................

186.2 DIFFERENTIAL & SINGLE ENDED INPUTS ......................

206.3 COMMON MISUNDERSTANDINGS .............................

206.4 GROUND LOOPS ............................................

206.5 LOW PASS FILTERS ..........................................

216.6 A/D RESOLUTION & ENGINEERING UNITS ......................

226.7 ENGINEERING UNITS ........................................

226.8 CURRENT LOOP (4-20 mA) ....................................

236.9 NOISE ......................................................

This page is blank.

1.0 SOFTWARE INSTALLATION

Before installing the board, install and run InstaCal. This package is the installation,
calibration and test utility included with your board. InstaCal will guide you through
switch and jumper settings for your board. Detailed information regarding these
settings can be found below. Refer to the Extended Software Installation Manual for
InstaCal installation instructions.

2.0 HARDWARE INSTALLATION

2.1 INTRODUCTION

The CIO-SSH16 is a signal conditioning accessory board designed to improve the
performance of a multi-channel analog input board (such as the CIO-DAS16)
wherever channel to channel skew must be minimized. The CIO-SSH16 is shipped
with four channels installed but components for additional channels can be purchased
for up to 16 channels of signal conditioning. As an accessory, it is mounted external
to the PC. It may be placed in the open on your bench top or in a case.

P18 to Analog Input Board

Figure 2-1. Board Cabling

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There are two cables used with CIO-SSH16; a signal cable and a power cable. The
power cable (C-PCPOWER-10) is supplied with the CIO-SSH16.

The power cable is black with two white MOLEX connectors. One end mates with
the J3 connector on the SSH16 and the other mates with any one of the available PC
power expansion plugs inside the PC.

The signal cable (C37FF-# or C37FFS-#) is a 37-conductor cable with 37D female
connectors at each end. One end plugs into the P18 connector of the CIO-SSH16, the
other plugs into the analog connector of a compatible analog input board (such as the
CIO-DAS16). (Figure 2-1).

2.2 POWER CABLE

A separate power cable is required because the CIO-SSH16 draws 1 amp from the
+5V supply to power the chips and the DC/DC converter which supplies the analog
components with +/-15V. This is more current than the C37FF cable should carry.
The C-PCPOWER-10 cable included with the CIO-SSH16 provides ample current
carrying capability.

The C-PCPOWER-10 power cable has two connectors, one male and one female.
The male end has metal pins, the female end, metal sockets.

The male connector will mate with any of the unused PC power expansion plugs
inside your PC. It is likely that there are unused plugs attac hed to wires which come
from the PC power supply on your PC. If not, order the C-PCPOWER-Y adapter to
add another connection. Plug the male end of the C-PCPOWER-10 power cable into
one of the unused power connectors.

Run the C-PCPOWER-10 power cable out the back of the PC. Use an expansion slot
or other orifice. If you prefer a connection external to the PC, the BP-POWER
adapter is available to bring the power connector out to a bracket that mounts in an
unused expansion slot.

WARNING

Use care so that the C-PCPOWER-10 power cable is not pinched by
the PC case. If the cable were severed, a serious short circuit would

result, possibly damaging your computer.
Power to the SSH 16 is supplied via a four pin MOLEX connector. This connector is
the exact mate of the standard PC Power supply expansion power connector. The
expansion power connectors are located inside the PC and carry +5V, +12V and
Ground. They are used primarily for disk drive power, but, there are more power
expansion connectors than you are likely to use (Figure 4-2) .

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The SSH16 requires 1 Amp of +5 volt power.
You may supply this power from the PC, as we
recommend, using the cable supplied, or you
may use an alternate power supply.

Figure 4-2. Power Connector

Caution on using alternate power supplies: The analog interface from the SSH-16 to
the CIO-DAS16 is a single ended voltage signal connection. As such, it is will not
reject errors induced by a potential difference between the PC power supply and the
alternate supply you use to power the SSH16. Please be certain the PC power supply
and alternate power supply share a common ground.

2.3 SIGNAL CABLE

The CIO-SSH16 signal connector is nearly
a mirror of the CIO-DAS16 signal cable in
16 channel mode (Figure 1-2). There are
two 37D connectors on the CIO-SSH16
wired in parallel. The second, P19, permits
daisy chaining signals to other signal
conditioning or screw terminal boards.

Use any 37 conductor ribbon cable with
female D-37 connectors to connect a
CIO-SSH16 to a CIO-DAS16 or other
compatible analog input board. The cable
length should not exceed 10 feet.

P14, DA0
N/C
P14, GND
P14, IP1
P14, IP3
P13, OP1
P13, OP3
P13, OUT0

P13, +5V

P16, DA1O
P16, S/H
P16, IP0
P16, IP2
P15, OP0
P15, OP2
P15, CLK1
P15, OUT2

Connect one end of the signal cable to the

P18 & P19

analog input boards analog connector and
the other to the CIO-SSH16 P18 connector. Figure 1-2 Signal Connector Pin-out

A shielded cable (C37FFS-#) is preferable if EMI or RMI is present with sufficient
energy to interfere with noise free measurements. The connection between the
CIO-SSH16 and the analog input board is single ended so signals on the cable have no
common mode noise rejection.

The signals labeled P13, P14, P15 & P16 (Figure 1-2) correspond to the four screw
terminal blocks where o ther signals co ming from or going to your A/D boa rd may be

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connected. The nomenclature on the CIO-SSH16 corresponds to CIO-DAS16 signals.

2.4 ANALOG INPUT BOARD SETUP

The analog input board must be configured for single-ended input. If the board you
are using with the CIO-SSH16 supports both 8 channel differential and 16 channel
single-ended configurations, set the board to 16 channels single-ended.

You may also need to configure a jumper on the analog input board to supply the
sample-hold signal to the CIO-SSH16. The SSH16 must have a SAMPLE / HOLD
signal in order to trigger the LF398 sample & hold chips. The LF398s sample the
input signal on each channel when the analog input board samples channel 0 and each
channels signal is held until the next time channel 0 is sampled.

Refer to the users manual for the analog input board you are using for details
regarding configuration of the analog input and the sample / hold signal output.

2.5 GAIN SWITCHES

Each amplifier has a quad DIP switch located
nearby. The four switches control the gain of one
amplifier. The gain settings are additive so a total
of 16 different gains (including 1) are possible.
The gain of a switch is added when the switch is to
the left and not added when the switch is to the
right.

Figure 1-5. Ganged Gain Switch

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3.0 SIGNAL CONNECTION

3.1 CONNECTOR DIAGRAM

The CIO-SSH16 inputs are screw
terminals which will accept 12-22 AWG
wire.

Each channel has a screw terminal for
signal high, signal low and ground.

3.2 ANALOG INPUTS

Analog inputs to the CIO-SSH16 may be connected in two different configurations.
In order of complexity, these are Floating Differential and Differential.

WARNING - PLEASE READ

Measure the voltage between the grounds at the signal source and

the PC. Use a volt meter and place the red probe on the PC ground

and the black probe on the signal ground. If there is more than 10

volts, do not connect the CIO-SSH16 to this signal source because

you will not be able to make any reading. If the voltage is more

than 30 volts, DO NOT connect this signal to the CIO-SSH16

because it will damage the board and possibly the computer.

3.3 FLOATING DIFFERENTIAL

A floating differential input is two wires from the signal source and a ground reference
resistor (10 Kohms is a typical value) installed at the CIO-SSH16 input. The two
signals from the signal source are Signal High (CH# HI) and Signal Low (CH# LO).

The reference resistor is connected between the CIO-SSH16 CH# LO and LLGND
pins.

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A floating differential hookup is handy when the signal source is floating with respect
to ground, such as a battery, 4-20 mA transmitter or thermocouple and the lead lengths
are long or subject to EMI interference.

The floating differential input will reject up to 10V of EMI energy on the signal wires.

WARNING!

Verify that the signal source is really floating. Check it with a

voltmeter before risking the CIO-SSH16 and PC!

3.4 DIFFERENTIAL

A differential signal is three wires from the signal source. The signals are Signal High
(CH# HI), Signal Low (CH# LO) and Signal Ground (LLGND).

A differential connection allows you to connect the CIO-SSH16 to a signal source
with a ground that different than the PC ground, but less than 10 V difference, and still
make a true measurement of the signal between CH# HI and CH# LO.

EXAMPLE:

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