Casella CEL CEL-281 - Manual (Page 68)

All communication is at CMOS logic levels, nominally 0 V and 5.0 V.
The connector is located behind a sliding panel in the bottom of the in-
strument. Figure 12 identifies the line connections in the socket.
3.6 Power Supply
The instrument is powered by four type AAA or LR03 manganese al-
kaline batteries that must be inserted in the battery holder supplied.
They have an operating life in excess of 16 hours.
Zinc carbon and rechargeable nickel cadmium batteries are not suit-
able as their shorter operating life gives the instrument a significantly
reduced operating time.
910009
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+
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Figure 13: Inserting the battery pack
How It Works
Page 60 - CEL-281 Operator's Handbook