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DG225715 Guarded Crossbar Scanner
The DG225715 Guarded Crossbar Scanner is an updated implementation of the Hewlett Packard 2911A.  Utilizing modern surface mount technology and COTS parts, Datagate Systems has lowered costs, improved performance and ease of maintenance while maintaining full, unit level, two-way interchangeability with both the HP 2911A and MDA 72D225715-1001. 

In it's original form the 2911A Guarded Crossbar Scanner offered users a choice of 600 1-wire, 300 2-wire, 200 3-wire, or 100 6-wire inputs permitting guarded 2-wire voltage or 4-wire resistance measurements.  Various options offered up to 10 user selectable output channels. Mechanically the HP 2911A consists of a 10x10x 6 open frame relay matrix, construction of the matrix physically prevents more that one address from being energized at a time thus preventing inadvertent cross connections.  The output from the matrix is routed through a further series of open frame relays to the selected output.  Inputs to the unit are made utilizing a proprietary 30 pin non-standard spaced connector.

In the late 1970's McDonnell Douglas Aircraft manufactured a version of the Crossbar Scanner under the part number 72D225715-1001.  This unit utilized custom hermetically sealed relays to perform the switching tasks. This unit is 2-way interchangeable with the HP unit at the unit level.

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DG225718 Crossbar Scanner Motherboard

The motherboard contains the output steering relays and both the X and Y addressing relays, along with connectors to receive the 10 daughter cards. Additionally there is a signal test port to assist in troubleshooting systems level problems.

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DG225721 Crossbar Scanner Daughter PCA

The Daughter card consists of 10 user selectable input channels 6 wires wide with one output channel. Input isolation is further insured by the use of an isolation relay located between the channel relays and the card output. Input to the PCA utilizes 2ea 30 pin inline connectors matching the HP 2911A format. As the mating connector is not available, an optional adapter PCA is available.

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DG225715UPG - 72D225715-1001 Upgrade

This product replaces the existing OEM PCAs with a new DG225728 and 10 each DG225715 PCAs. The customer returns the OEM unit to Datagate Systems and we install the new PCAs. At the completion of the upgrade the upgrade unit is tested in our HP 9500D Automatic Test Set. The upgraded unit and the removed PCAs are then returned to the customer.

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DG2911UPG - 2911A Upgrade

This upgrade path requires the customer to return his 2911A to our depot. In the depot we remove the output connectors and reinstall them in a new cabinet. The completed unit is tested in our HP 9500D Automatic Test Set.

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  6. DG2911UPG 2911A-086 Scanner Upgrade