There are a total of 5 Datacrons on the Planet Belsavis.
Datacron 1 - Republic and Empire
Codex Entry- Galactic History 72: The Fall of the Covenant
Coordinates: -500, 768
This Datacron is located within High Security Section. There are 2 Datacrons located in this location, this one and the +4 Endurance one which we'll cover next. So, getting this Datacron is easy, just go to the canyon at -830, 790 and follow it until you reach the Datacron.
Datacron 2 - Republic and Empire
Codex Entry - Galactic History 69: The Mandalorian Wars
Coordinates: -992, -449
The Datacron is located in the North-West side of High Security Section, inside a cave, at its end. The cave entrance is located at -905, -387 and the Datacron is guarded by a lvl 42 Champion. You need to fight your way from the start, the cave is full with elite and silver mobs.
Datacron 3 - Republic and Empire
Codex Entry - Galactic History 70: The Covenant Acts
Coordinates: -1914, -475
The Datacron is located within the Maximum Security Section - Ancient Prison Approach, with the entrance at -2240, -142. You'll notice some Esh-Kha Scouts at your right side and a huge wall behind them with some rocks at the bottom. If you face that wall, you'll see there's a path on the left side into the rocks. Take that path up and follow it - always kiss the left wall and follow the path untl you have the molten lava river in your left (down). Keep straight ahead, you at some point you'll see the Datacron in the distance. You need to keep left and the path will take you slightly down, on to rocks, to the Datacron.
Datacron 4 - Republic and Empire
Codex Entry - Galactic History 68: The Mandalorians Return
Coordinates: -785, -1930
This Datacron is located in The Tomb area and it's a bit tricky to get, but if you're careful, it's easy. First of all, you need to ignore that laser bridge connecting the rocky area where you stand and the Datacron island (-710, -1901). It's either bugged or a trap so you need to go around the right to -712, -1951 and face the bridge. From that position, you'll see a small rock ledge. Use your speeder and jump to that ledge, at its right. You may fail a couple of times but it's doable and it needs some practice. From that ledge, you need to jump to the ledge on your right. Now you need to go around the rock until you're facing the laser bridge entrance. You need to jump over the bridge's entrance and land on the rocks on its left. Now you need to go around the left of the Datacron, moving on these rocks. Halfway towards the Datacron, you'll notice a higher rock formation that cannot be jumped onto. If you look carefully, you'll notice a smaller rock ledge on its right, that can be climbed. Be very careful, it's a very sensible step and you might fall and die, resetting the whole process. From this ledge (its top), you can jump on the higher rock formation then move along the rocks until you find a small ledge across the Datacron (-801, -1912). From that ledge, using your speeder, you can jump on the Datacron island. After you take the Datacron, there's a Rakata Transported behind it, which it teleport you. (or you can commit suicde, whatever fancies you).
Datacron 5 - Republic and Empire
Green Matrix Shard
Codex Entry - Galactic History 71: The Muur Talisman
Coordinates: -315, -2172
The last Datacron is located in the center of the Tomb Area, in the Cave-Under-Tree area. Getting this Datacron requires you have 4 x Rakata Energy Cube
. In the center of the Tomb Area, you'll find a large tree with a passage underneath it. You need to go inside and take the elevator down. You need to insert the 4 cubes into the machinery which releases the Datacron. If you decide on doing this Datacron with a group, it's sufficient that 1 player unlocks the machinery (there's no need to have 4 cubes per player).
Rakata Energy Cubes spawn points:
-763, 882 (High Security Station)
-700 -1960 (you can take this cube on your way to the Datacron 4)
-483,142 (there's a shot-down Freighter near by)