There are many different types of connector for pH electrodes and these will depend on the meter brand and the electrode type. The most common connector in the UK is the BNC connector which is usually found on combination or pH half cell electrodes and is characterised by its locking twist action.
The DIN connector is common in central Europe. The US connector is so called for obvious reasons. This is usually found on Radiometer meters for example.
S7 or DIN-EL is the most common connector for leadless electrodes. With these electrodes you detach the cable at the electrode end to replace a probe rather than the meter end. These types of electrode are becoming more popular as they save having to buy a new lead and connector every time and are ideal for situations where the cabling is fixed e.g. robotic platforms. They will have a male S7 that connects to the DIN-EL connector on the electrode. The opposite end of the lead will then have whatever connector is required for the meter. This allows you to use electrodes from a wider range of manufacturers to satisfy specific technical requirements.
The other type of plug you will see is a banana plug and these are usually only found on reference half cells. If you look on your meter you will probably find a seperate reference input next to the BNC or DIN connector.
Camlab provide electrode adapter cables here which will allow you to connect probes from alternative manufacturers to your pH meter.
A WORD OF WARNING: Some modern pH meters use pH probes that have an integrated temperature probe and these will generally have a meter specific connection so you are locked in to using that manufacturers probes. You may be able to use a combination electrode without temperature compensation or with external compensation but this will depend on the meter. Please call 01954 233 120 for more assistance.