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Cable network

In this section, we will learn how to assemble cable loops.

About the cable network​

The on-board cable network is necessary for information exchange between the subsystems and the central computer, as well as for supplying power to the subsystems.

Satellite subsystems have two redundant connectors for connecting to the on-board network. Thus, the device connected to the on-board network is not only available for information exchange with it, but also provides the opportunity to connect through itself with a "garland" of subsequent subsystems in the circuit.

The information network is built on a bus architecture using serial interfaces RS-485. To facilitate installation, the power lines and the information network are combined into one loop. The subsystems are connected via the DB-9F connector ("mom") on the harness side and DB-9M ("dad") on the device side. Since different layout of the designer elements is possible, the determination of the length of each loop, its configuration, and ultimately the manufacture remains with the user.

Preparation​

  • Take from the OrbiCraft kit: a crimper, wire cutters, a loop coil, 2 "mom" connectors, a loop tester and a 12V power adapter.
  • Cut the cable of the required length from the coil of the nine-channel cable included in the set with wire cutters.

Assembly of the loop​

  • Insert the yellow insert included in the kit into the crimper.
  • Place the connector in the yellow insert under the center of the crimper clamping bar.
  • Holding the crimper with the connector with one hand, place the end of the cable into the connector with the other hand.
  • Use the crimper to clamp the connector with the inserted end of the cable until a characteristic click sounds.
  • Make sure visually that the connector is locked.
danger

Make sure that the cable is completely in the connector, but does not stick out too much on the back side.

Before making an effort to snap, press the latch slightly, make sure that the cable cores fall evenly between the contacts and only then finally snap the connector.

  • Repeat the algorithm of actions for the second end of the cable with the second connector "mom".
danger

When crimping the cable, it is important to remember that the installation directions of the connectors coincide, as shown in the illustrations below.

Correct assembly (Picture 1):

Correct assembly of the two-point loop

Picture 1. Correct assembly

Incorrect assembly (Picture 2):

Incorrect assembly of the two-point loop

Picture 2. Incorrect assembly

tip

The existing pinout of the connector (the purpose of each of the contacts) minimizes the likelihood of damage to the equipment if the cable is improperly manufactured by the user. However, it does not guarantee that the device cannot be disabled in principle. It should also be noted that the manufacture and refinement of loops by the user does not require special skills and tools.

tip

It is possible both to connect all network devices in series using point-to-point cables (as in Figure 3), and to create branches when using cables with more than two connectors.

Serial connection of devices

Picture 3. Serial connection of devices

danger

The cable for connecting the camera "papa-papa" should not be longer than 40 cm.

danger

It is forbidden to connect devices that are not intended for use "on board" (a "ground" HF receiver and a "ground" UHF telemetry receiver) and on-board network devices to the same cable network. It is especially important to ensure that the USB-RS485 ground segment connection cable and the on-board power supply system (PSS) do not end up in the same cable network. Otherwise, the components of the constructor may be damaged.

Checking the loop​

  • Connect the loop tester to the 220V network using the supplied 12V power adapter.
  • Plug the assembled cable into the appropriate connectors on the cable tester. The green light "OK" should light up.
danger

If you still have the yellow "Break" light on, then you have a circuit break. Most likely, you have not fully compressed the cable.

If you have a red light "Short circuit", it means either you damaged the insulation of two adjacent channels when compressing the loop, or you incorrectly placed two connectors relative to each other. Try to re-compress the cable by following the instructions above.