INTRODUCTION
I-E96-313A
2 - 1
SECTION 2 - DESCRIPTION AND OPERATION
INTRODUCTION
This section explains the output circuitry, control logic, data,
logic power and connections for the Digital Slave Output (DSO)
module. The DSO is a digital signal interface between a
Multi-Function Processor (MFP), Multi-Function Controller
(MFC) or Logic Master Module (LMM) and process field devices.
The master module communicates with its slave module on a
12-line slave expander bus shown in Figure
. Each slave on
the bus has a unique address set by its slave address
dipswitch (S1).
DIGITAL OUTPUTS
Digital signals have two states, ON or OFF. The DSO module dig-
ital outputs switch voltages of 24 VDC at 250 mA. This voltage
energizes (turns on) and de-energizes (turns off) a field device.
MODULE BLOCK DIAGRAM
The DSO consists of registers, buffers and interface circuits.
They control the digital output switching, and transmit slave
operating status back to a master module. Open collector tran-
sistors provide the switching functions. Optocouplers isolate
the module circuits from the process.
The DSO has two sets of circuits to control its sixteen outputs.
One controls group A outputs; the other controls group B out-
puts. Both receive their data from a single slave expander bus
interface. Figure
is a block diagram of the DSO module. It
illustrates signal flow through the module. Figure
shows
the digital output circuit.
Digital Output Circuits
Sixteen open collector transistors in the digital output block
function as digital switches. Optocouplers for each output pro-
vide isolation between the module circuits and the process field
device. All outputs are normally de-energized (OFF) until a sig-
nal from the data selector block causes them to energize (ON).
The output circuits provide 300 volts isolation between output
and logic circuits, and other output channels.
NOTE: Due to the number of pins on the P3 connector, twelve out-
puts are separate while the remaining two pairs share output termi-
nals. The positive (+) sides of outputs 7 and 8 are tied together for
each group (refer to Table
). They are not isolated from each
other, but are isolated from the module circuitry.
