There were about 4 scheduled bus departures per day in 2015 but the introduction of the modern and faster min vans for shorter trips has seen the number of departures shrink to 1 only, departing from the Nong Khai bus station at around 1030 to 1100 hrs each day and reaching Nakhon Phanom at around 1800 hrs.
This bus was run by a husband and wife team (and possibly the daughter as cargo assistant), a very relaxed and helpful crew who seemed to look after each other as well as the passengers. The driver was also an accomplished mechanic who managed to change over the steering pump during a 15 minute scheduled top in Buengkan.
It cost 200 baht and takes 7 hours to cover the 320 km route along the Mekong River. The bus stops at station areas at Phon Phisai, Pha Kat, Beungkan (big new station on highway – replacing the stop in town at the clock tower) and lastly at Ban Phaeng. These stops are for between 5 and 10 minutes but there are also stops to collect and drop people or cargo off along the way. There are toilet facilities at each stop with a charge of between 3 and 5 baht, although cleanliness is a bit average.
The bus was air conditioned and while ancient (speedometer still in miles per hour) was quite comfortable with decent leg room and intact seat covers.