The D4591 Display/Keypad incorporates a 2-line X 40-character back-lit LCD display with a 3-row X 8-column sealed keypad. Back-lit LCD technology at 0.19" character height provides both high visibility in low light conditions and high character density. The keys on the keypad are spaced at 0.75" spacing. The D4591 offers a low cost, flexible and highly functional solution to man machine interface with the M4500.

The D4591 is an option that can be used with any of the back-panel mounted versions of the M4500 including the M4500, M4501, M4508, M4509, M4510, M4512, or M4513. The display is interfaced with these modules via a 26 pin ribbon cable. Communications is parallel at TTL levels, therefore, the display must be mounted in close proximity to the M4500 (maximum cable length is 8 feet).

For the M4502 and M4503 door mount versions, the D4591 display/keypad is actually fully integrated in the module. In all cases, the display is equipped with a gasket and is fully sealed to NEMA 12 levels to prevent the ingress of contaminates to the display. An optional NEMA 4X bezel is available for wash down applications as well.

Display Operation

The display can be used as a general purpose operator interface or can be used to implement the PLS programming commands.

When used as a general purpose interface, complete control of the display is provided through commands accessed through the user program of the PLC section. Commands such as: "position cursor", "clear display", "enter characters into display", "blink character", as well as an ASCII string conversion system function allow easy and complete control of the display directly in the M4500 user's program.

The PLS program commands are resident in the firmware of the M4500 and can either be enabled or disabled in the user's program. When enabled, the display performs as a programming terminal for the PLS section.

The keypad of the D4591 is a 3-row X 8-column sealed keypad which can either be used as a general purpose operator interface or to implement the PLS programming commands. Key depressed decode is performed automatically by the M4500 with the key number depressed mapped directly to an internal memory location.

The keypad overlay itself simply contains clear windows over the keys. Customization of the keypad is performed by placing a placard behind the overlay (between overlay and keys) with the desired key legends. This allows complete customization of the keypad in quantities as low as one.