REV-E boards in development.

This rev has all the features of rev-d and also has additional resistor pads for termination, pull up and pull down of RS-485 drivers. These are all installed by default, to have identical REV-C functionality these parts will need to be removed.

REV-D boards available now.

This rev has all the features of rev-c and also has additional resistor pads to allow selection of full duplex without setting processor pins, and pull ups on the processor serial receive lines were also added to prevent spurious reads. If low voltage TTL serial is needed the board can also be configured as a pass through that connects the processor pins directly to the rails.

kardcom_schematic_plpb-0042-rev-d.pdf

The Serial Driver Kard™ has one RS-232 level shifter (Serial 1) and two half duplex RS-485 level shifters (Serial 2 and Serial3), the two RS-485 level shifters can be used together as a single RS-422 level shifter. All level shifters are are broken out on Rail C. The two RS-485 level shifters can be tied to the H-bus connector though user installed zero ohm jumpers.

kardcom_schematic_plpb-0042-rev-c-proposed.pdf

The REV-B Serial Driver Kard™ has one RS-232 level shifter (Serial1) and two RS-422 level shifters. The RS-232 and one RS-422 (Serial3) level shifter are broken out on Rail C and the final RS-422 (Serial2) level shifter is sent to the H-bus. The RS-422 driver chip used on this version of the board always had the Tx lines asserted and prevented multi drop communications. This lead to the REV-C version.

kardcom_schematic_plpb-0042-rev-b.pdf

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