increment
Increments the outgoing packet opcode counter alone, without the payload increase. We require a special function for this since our JS5Service implementation fragments the payloads into blocks of X bytes. Due to the nature of it, we may only have a single packet header, but a hundred slices of that packet's payload.
Parameters
opcode
the opcode of the packet which was sent. In the case of JS5 response, since the JS5 protocol only has a single possible response, there is no opcode system supported for it. As such, we use a filler opcode of 0 to fit our needs.