CABLING TOGETHER INSTRUNET HARDWARE
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Designing Your instruNet Network

instruNet hardware is 100% plug and play for all computers.  instruNet does not use dip switches, DMA, low memory, interrupts, and I/O addresses.  All you need to do is plug the Controller board into your computer, connect your network devices, slap a terminator onto the end of your network and run the instruNet World software.  The instruNet driver automatically determines the physical locations of all installed Controllers and Network Devices.

Please keep in mind the following when designing and constructing your network:

1.   Install as many controllers as desired
The number of available slots determines the number of controllers (i.e. networks) that can be installed, and simultaneously run, on one computer.  The software numbers each controller in the order that they are found in the computer ("netNum" ranges from 1 to # of Controllers).  Each controller manages it's own network of devices.  In most cases, only one controller is necessary.  The advantage of multiple controllers is that each is its own real-time machine, and more controllers can do more things simultaneously.

2.   Install up to 8 Devices on each Network
One can attach, in daisy-chain configuration, up to 8 Network Devices to each instruNet Controller.  Each Network Device has two DB-25 connectors, one for network input (male), and another for network output (female).  To connect a chain of Network Devices, one must connect each input connector to each output connector via a DB-25 Male/Female cable.  The Controller is attached to the first device in the chain, and an instruNet Terminator is attached to the far end of the chain.  Due to the male/female polarization, the network cannot be installed incorrectly with instruNet Male-Female cables.

3.   Each Controller includes Timer I/O Channels
Each Controller (except iNet-230 PC-Card) provides 10 Timer I/O channels.  Each channel can be programmed as a digital input, digital output (0V/4V TTL compatible), clock output, or period measurement input.

4.   Each Controller includes one Terminator
One instruNet Terminator must be installed at the end of each network chain.  This terminator mates with the output connector of the last device.  instruNet Controllers include an instruNet Terminator, therefore they do not need to be purchased separately.  Caution: Do not use a SCSI Terminator in place of an instruNet Terminator -- they are different. 

5.   Each Network Device includes one cable
Each instruNet Network Device is shipped with one 10foot DB-25 Cable Male/Female cable for purposes of configuring your network.

6.   You can purchasing your own cables
If you want a specific cable length, you can purchase your own DB-25 male to DB-25 female, shielded, wired point-to-point (i.e. pin X to pin X) cables.  We recommend 24 gage wire for > 4 meters; however 28 gage is fine with ≤4m.  Twisted pairs are recommend for >4 meters with the following wires twisted: 1 & 14, 2 & 15, 3 & 16, 4 & 17, 5 & 18, 6 & 19, 7 & 20, 8 & 21, 9 & 22, 10 & 23, 11 & 24, 12 & 25 (these are physically next to each other in the connector).  Also, it is recommended that the drain wire (which is attached to the shield) be connected to the housing and pin #1 (GND) on both connectors.  For more information on cables, please see Third Party instruNet Cable Suppliers and Low Capacitance Cables.

A supplier of high quality twisted pair, low capacitance, double-shielded cable without connectors is Belden, Inc.  The Belden Cable Part #8112 Low Capacitance RS-485/RS-232 cable is available in 100ft, 500ft, and 1000ft lengths with 12.5 Pairs and a copper braided shield.  This cable features 24 gage wire, 41pF/meter between pairs, 72pF/meter between a wire and the shield, and 78ohms/killometer wire resistance

7.   Minimum Base System
One Controller and one Network Device is all you need to purchase to digitize waveforms, save them to disk, and view them.

8.   Maximum Sample Rate
As the physical length of the network increases, the maximum aggregate data acquisition sample rate decreases from 166Ks/sec maximum with a short network (e.g. 5 meters) to 4.15Ks/second aggregate with a long network (e.g. 300 meters). 

This maximum aggregate rate applies to a batch of input channels.  For example one instruNet network can support 4 voltage input channels at a maximum rate of 41.5Ksamples/sec for each channel (i.e. 166Ks/sec throughput).  The same network would allow 8 channels of voltage input to be acquired at 20.075Ks/sec per channel.  The maximum aggregate rate can be increased by installing additional instruNet networks and controllers.  For example, two controllers could support 332Ks/sec aggregate throughput if run simultaneously.

When the instruNet powers up, it empirically tests (i.e. it test the cable impedance) of the network to determine its maximum throughput rate (i.e. 4.15K/sec to 166Ks/sec).  The maximum rate is decreased by: additional network devices, longer aggregate network cable length, non-twisted pair cables, and thinner cable wire (e.g. 28 gage instead of 24 gage).

For more information on sample rates, please refer Sample Rate Vs. Integration Time Vs. Noise and i2x0/i100 Maximum Sample Rates.

9.   Turn power OFF when cabling
Always turn the computer and powered Network Devices Off before adjusting network cables.

10. Large networks require external power supplies
The instruNet network cable provides power from the computer to the external Network Devices.  As the number of devices increases (more current drawn), and the cable lengths increases (more voltage drops), it becomes increasingly necessary to add an external power supply for the Network Devices.  We recommend adding an external power supply if your cable is > 50 meters, or for every 4 Network Devices after your 3rd Device.  In other words, only add an external power supply if you have more than 3 network devices, or if your network is longer than 50 meters.

Diagrams of Typical Cabling Scenarios

The following illustrates how to connect instruNet devices to each other, and to the computer.

i200 PCI Controller to 1st Device

i230 PCMCIA Controller (Rev 2, > 6/4/04) to 1st Device

1st Device to Further Devices

i312.8xx Power Supply

i330 Optical Isolator

Legend

	Cpu	Windows or Macintosh Computer
	3m Cable	3 meter DB25 Male to DB25 Female Cable, included w/ each Device
	Device	instruNet Device (e.g. i100), DB25M input, DB25F output
	Power	110Vac or 220Vac power outlet
	Term	instruNet Cable Terminator included w/ each instruNet Device,  DB25 Male Connector
	i200	i200 PCI Controller Card, DB25 Female Connector
	i230	i230 PCMCIA Controller Card (Rev 2, >6/2/04), Pcmcia-25 Connector
	i230-Cable	"Pcmcia25 to DB25F" Cable, included w/ i230 Rev 2
	i300	Power Adaptor Cable, included with each i312.8xx Power Supply (DB25 Male instruNet input, DB25 Female instruNet Output, DIN5 Female power Input)
	i312	instruNet Power Supply (iNet-312.8xx, Rev 2, >6/2/04), 5Pin DIN Male Connector
	i330	Optical Isolator (DB25 Male instruNet input, DB25 Female instruNet Output, DIN5 female power Input)

Photographs of Typical instruNet Hardware Systems

i200 PCI card i100B Data Acquisition System
i230 PCMCIA card for Laptops i100B Data Acquisition System i312.8 Power Supply
i200 PCI card i100B Data Acquisition System i330 Optical Isolator i312.8 Power Supply