You can use either a 9-pin (rs-422,P2) or MMC

Using 9-pin -

1) make sure you have OS version 2.1 or later in MX2424
2) The MENU 340 on MX2424 needs to be changed from RS-422 to P2in
3) Hit (Shift+Midi MC/EXT CTRL) on the DM24 which brings you to the Machine control page
4) Press the soft key below SETUP
5) On the bottom left of the LCD there are 2 choices - Use the cursor to choose RS422/MIDITHRU and press enter
6) Press the soft key below MACHINE CTRL on the LCD
7) Use the Cursor keys to point at LIST AUTO DETECT and press ENTER
8) The MX2424 will show up in the screen
9) On the left side there is a column labeled STATE - If your connection is made properly then you will see a double sided arrow
10) Use the cursor to point the cursor at the TRA (transport) circle and press ENTER
11) Now use your cursor keys to point to the REC semi circle -
use the data wheel to change the setting to 1-24 and press ENTER

**NOTE: you can use SMPTE time code from the MX2424 on the DM24 but you cannot use this time code to trigger the DM24's automation. For this, you must either use a 1/4 in to RCA cable and send SMPTE from the MX2424 to the DM24