Field modules, also known as slaves, or slave modules, come in many different forms. The most common are "box" type and "rail" type. Box type is pretty self explanatory, being a small box with cue terminals. See pictures below. The box is good for groups of mortars, or a group of low level devices such as cakes. A rail type can be a hardwood or fiberglass rail, with cue terminals a measured distance apart. Another "rail" type comes in a flexible form and is sometimes called a "cable slave". A standard rail has hard mounted cue terminals that might make it difficult when spacing between different size mortars varies. A cable slave will have extreme flexibility when it comes to placement of fireworks, and will potentially save a whole lot of "zip" wire used to extend electric match leads to a cue terminal.
A typical slave module will consist of these main parts:
Each slave module will have a number of cue terminals, the number depending on the firing system design. Each terminal is typically a stereo speaker type of connector with a red and black terminal. There are a few other variations of cue terminals; however, this also depends on the firing system design. The electric match attached to the firework plugs directly into these terminals.
Firing Cable Interface
The interface can consist of just a loose cable end hanging out of the firing control module, or more commonly, a connector which sits flush on the face of the module, very similar to the firing board. For the case of the cable slave, it has a 25 pair amphenol connector at each end. It doesn't matter which end is plugged into the firing cable. The advantage of being able to interface to it at either end is that you can maximize distance between your firing board and your fireworks setup by plugging in the end which is closest to the firing board. This also means you can string them end to end if you have fireworks that need to fire simultaneously from multiple positions on the same cue.
You will typically have a simple screw terminal which a ground wire will attach. Some firing systems are internally grounded through the firing cables and do not require this extra ground line.