Raytheon DIDS-400 402-2M10 Installation And Maintenance Manual page 47

DIDS-402 -2M1 0
Para 3-6.4
is sent to the modem to indicate that the Display Terminal has been
turned on. The DIDS-402 interface signals are bipolar as follows:
Data Signals
MARK -8 ±2 V (logical 1)
SPACE +8 ±2 V (logical 0)
Control Signals
OFF -8 ±2 V
ON +8 ±2 V
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