https://4dsystems.com.au/mwdownloads/download/link/id/211/MOTG-RS232 3D PDF:
DISMON1275 is the article number for MOTG-RS232

The 4D Systems MOTG modules are designed to attach primarily to the gen4 range of display modules, attaching via an interface board which mounts to the back of the gen4 display module. These can also be used for other platforms, and for development using a breadboard.

The MOTG range is currently made up of 5 MOTG modules.

MOTG-RS232 - this module enables RS232 communications, for interfacing with an external RS232 devices.

MOTG-RS485 - this module enables 2-wire RS485 communications, for interfacing to 1 or more external RS485 devices.

MOTG-WiFi-ESP - this module uses the ESP8266 wireless bridge, for interfacing to WiFi networks/devices or to other MOTG-WiFi-ESP modules.

MOTG-BLUETOOTH - this module uses the Microchip RN4870 Bluetooth module, for interfacing with Bluetooth devices.

MOTG-MP3 - this module features the 4D Systems SOMO-II audio processor, and features an on board Mono amplifier and Stereo DAC output.

There are 4 interface boards available currently, 3 of which are used specifically to mount MOTG modules on to gen4 display modules. 

The gen4-MOTG-AC1 is sized to suit fitment on to the back of the 2.4" Diablo16 gen4 display modules, but can also mount to the 2.8", 3.2" and 3.5" Diablo16 gen4 display modules too. It features a single MOTG interface, a pass-through 30 way FFC connector, and an opening in the PCB so access to the microSD card on the gen4 display module.

The gen4-MOTG-AC2 is sized to suit fitment on the back of the 3.2" Diablo16 gen4 display module, but can also mount on to the 3.5" Diablo16 display module. It features two MOTG interfaces, a pass-through 30 way FFC connector, on board audio amplifier and speaker, and an opening in the PCB to access the microSD card on the gen4 display module.

The gen4-MOTG-AC3 is much the same as the AC1, but is designed for the Picaso range, from 2.4" to 3.2".

These 3 interface modules are designed for the smaller size gen4 displays, as mentioned above, however they can be used for the larger gen4 displays too. They will not locate on the plastics like they do on the smaller modules, however they are functionally compatible. Additional Interface modules will be available in time to better suit the larger displays.

The MOTG-BREADTOOTH is a simple interface board designed to break out the pins on a single MOTG module, so they can be used on a Breadboard or wired to another device or host. It features 2.54mm (0.1") breadboard friendly pin spacing.

For more information, please refer to the MOTG Datasheet, which features all modules and interface information.