Recently I acquired for a client the subject switch. Much to my surprise a very important component was missing.
The missing component is the secondary DC jack on the back of the enclosure that supports 48-57 V power supply
https://mikrotik.com/product/crs112_8p_4s_in
CRS112-8P-4S-IN is an eight Gigabit RJ45 port PoE switch, that offers different power output options: autosensing 802.3af/at PoE/PoE+ and Passive PoE, and four SFP ports provide optical fiber connectivity options to support uplinks of up to 1 Gbps.
CRS112-8P-4S-IN is equipped with 12 independent switching ports. 28 V 3.4 A power supply is already included in the box. There is secondary DC jack on the back of the enclosure that supports 48-57 V power supply (not included, can be purchased separately - product codes 48POW (1.46A 70W) and 48V2A96W (2A 96W)). CRS112-8P-4S-IN can power 802.3af/at devices if 48-57 V DC input is used (unit will automatically detect and provide correct power to devices). Max current is 1 A per port if input voltage is 18-28 V, 450 mA if 48-57 V. Total limit is 2.8A@24V and 1.4A@48-57V. PoE-Out is passed over mode B 4,5 (+) and 7,8 (-) pins
How did I find out: I received the CRS112-8P-4S-IN from ISPsuplies [Ottawa Canada] – set it up to test. After configuration I plugin a Unifi UAP-AC Pro into port 1 and it would not light up obviously the wrong power — so I then proceeded to order the 48V2A96W power supply — but where do I plug it in ??? … so I read the description quoted above and looked for the secondary DC jack on the back of the enclosure that supports 48-57 V power supply … MUCH to my surprise no such component was present Believe it or Not.
Following is picture of what the backside of the CRS112-8P-4S-IN should look like … mine does not look like that at all.
