For Additional Information About Optical Isolation verses a Standard IC on the Input of a Device see below

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ELM Video Technology, Inc.

DSI-4 and the DXI Optical Isolation, verses the DS4 Non-Ocptical Isolation

Input IC Comparison Table

Based on IC specifications, visit Texas Instruments website for individual IC specs.

	Standard IC SN75176AP	Optical Isolated IC 6N137	SN65LBC184
Isolation Type	Electronic	Optical	Electronic - Transient Voltage Suppression
Line Load (input impedance)	1/32 (apx 1.9mA Line Load)	1/2 (apx 25mA Line Load)	1/128 (apx .5mA Line Load)
Output (Stability with broken or loose wire)	*Miscellaneous (unstable)	*Stable	*Stable
DMX512 Conformity	Yes	**No	Yes

DS4 (Input IC)			Y
DSI-4 (Input IC)		Y
DXI (Input IC)		Y

*Circuit design and environment affect the output

**6N137 does NOT conform to the DMX512 standards and should work with most systems.

For more information about DMX512 standards visit - http://www.usitt.org/DMX512.aspx

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The Advantages of Optical Isolation on the input of a device

Potentially higher voltage isolation protection than a standard balanced input IC
Current driven input - in the event that 1 of the wires of the 2 wire balanced DMX line stops working the output of the Iso chip will go high.

The Disadvantage of Optical Isolation on the input of a device ( See Texas Instruments web site chip # 6N137 for specs )

Requires a higher current than a standard balanced input IC. (Connect only 16 devices on the daisy chain instead of the normal 32). If the Opto device is connected directly out of the console this should not be a problem.

The Advantages of IC (65184) on the input of a device ( See Texas Instruments web site chip # SN65LBC184 for specs )

Offers protection between the output device and the input device using Transient Voltage Suppression.

Hi Z input (less line load on the daisy chain)

Without a connection (floating input) the IC has a high output - won't send miscellaneous data

The Disadvantage of IC (65184) on the input of a device

The 65184 IC or a standard input IC - if 1 of the wires of the 2 wire balanced DMX line stops working the output of the IC is miscellaneous (unstable)