Data Translation DT9871, User Manual

Page: 101 / 134

Principles of Operation
101
Digital Output Lines
TEMPpoint, VOLTpoint, and MEASURpoint instruments feature eight, latched and isolated
digital output lines. The outputs are solid-state relays that operate at ±30 V and 400 mA peak
(AC or DC). Switching time is 2 ms maximum.
Figure 35 shows the digital output circuitry.
Figure 35: Digital Output Circuitry
Digital outputs resemble a switch; the switch is closed if the state of the digital output line is 1,
and the switch is open if the state of the digital output line is 0. On power up or reset, the
digital outputs are disabled.
Channel-to-Channel Functional Isolation
Each TEMPpoint, VOLTpoint, and MEASURpoint instrument includes channel-to-channel
functional isolation of up to 60 V between digital I/O lines.
Resolution
Each TEMPpoint, VOLTpoint, and MEASURpoint instrument provides 8 bits of resolution for
the digital input port to accommodate the 8 digital input lines and 8 bits of resolution for the
digital output port to accommodate the 8 digital output lines. These lines are organized as
isolated, dedicated ports. You cannot configure port resolution through software.
Operation Modes
Using software, you can read from a single digital input line or the entire digital input port, or
write to a single digital output line or the entire digital output port. You can also return the
value of the entire digital input port in the analog input data stream if you want to correlate
analog input data with digital events; refer to
page 96 for more information.
1 of 8 Solid State Relays