Emerson Rosemount 702 - Discrete Output Circuits

91
Reference Manual
00809-0200-4702, Rev CA
Section 9: Operation and Maintenance: Models 702DX32 and 702DX42
February 2013
Operation and Maintenance: Models 702DX32 and
702DX42
Table 9-3. State table for Limit Contact and Opposing Contact
9.3 Discrete output circuits
Output circuits, measurement option code 42
The 702 transmitter has two channels that can each be configured for discrete input or output.
Inputs must be dry contact switch inputs and these were described in a preceding section of this
document. Outputs are a simple switch closure to activate an output circuit. The 702
transmitter output does not provide any voltage or current, the output circuit must have power
of its own. The 702 transmitter output has maximum switch capacity per channel of 26 volts DC
and 100 milliamps. A typical power supply for powering an output circuit can be 24 volts or
lower.
Note
It is very important that the polarity of the output circuit is as shown in the wiring diagrams,
with the positive (+) side of the circuit wired to the CH2 + terminal, and the negative (-) side of
the circuit wired to the CMN terminal. If the output circuit is wired backwards it will remain
active (switch closed) regardless of the state of the output channel.
Discrete output switch functionality
The discrete output of the Rosemount 702 transmitter is driven by the host control system,
through the Smart Wireless Gateway, and out to the 702 Transmitter. The time required for this
wireless communication from the gateway to the 702 transmitter is dependent on many
factors, including the size and topology of the network and the total amount of downstream
traffic on the wireless network. For a network that is constructed to our best practices, typical
delays in communication of a discrete output from the Gateway to the 702 transmitter are 15
seconds or less. Remember that this delay is only part of the latency that will be observed in a
control loop.
Note
The output functionality of the Rosemount 702 transmitter requires that the network is
managed by a version 4 Smart Wireless Gateway, with v4.3 firmware installed.
State Table for Dual Input Limit Contact Logic, or Dual Input Opposing Contact Logic Application Types
Value Name Analog Value Discrete Value
Reported
Value
False
Switch
Active
True
Switch
Active
Fault Travel
False
Switch
Active
True
Switch
Active
Fault Travel
False
Switch
Active
True
Switch
Active
Fault Travel
Default False True Fault Travel 0.000 1.000 NAN 0.500 240 242 243 241
All Others False Tr ue Fault Travel 0.000 1.000 243.0 241.0 240 242 243 241