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How the compatible PointGuard MDI 37-bit (MDI37) works
The PointGuard MDI 37-bit (MDI37) is a 125 kHz low-frequency proximity credential — the band most legacy prox readers use. Its data structure is 37-bit: leading even parity + 4-bit site code + 29-bit card number + trailing odd parity. When you present a credential, the reader decodes that exact structure and passes it to your access-control panel as a card number it recognises.
We build the compatible PointGuard MDI 37-bit (MDI37) by encoding the matching data structure onto a programmable T5577 / EM4305 chip. Once written, the credential presents the same bits, the same facility code, and the same card number your reader already accepts. That is what "compatible by specification" means: not a generic look-alike, but a credential engineered for the exact format your system expects, matched to your facility code and card-number range.
To order, tell us the part number or format printed on your existing PointGuard card, along with your facility code and card-number range, and our specialists confirm the encoding before anything ships. Bulk and reorder quantities are welcome — pricing is a fraction of OEM list, and every credential is verified to read on your existing equipment.
Also known as
MDI37 · PointGuard 37-bit · PointGuard MDI · MDI PointGuard
PointGuard and all other brand and product names are trademarks of their respective owners. Security ID Systems is an independent manufacturer and supplier of compatible access-control credentials and is not affiliated with, authorized by, sponsored by, or endorsed by these companies. Brand and format names are used only to identify the systems our products are compatible with.