DESCRIPTION AND OPERATION
MODULE DESCRIPTION
I-E96-308A
2 - 3
Externally Powered Normal Logic Level Input Mode
Set up the externally powered normal logic level input mode
with self powered input circuits isolated from the pulse pro-
cessing circuits. There are two available ranges that may be set
by jumpers J1 through J8 on the module. Range 1 is 4.0 VDC
to 6.0 VDC and range 2 is 21.6 VDC to 27 VDC.
Internally Powered Contact Input Mode
The 24 VDC input and output power supply uses the internally
powered contact input mode. It is used to sense open and
closed conditions in the input circuit. Set up this mode by
making proper dipshunt connections on the termination unit.
Voltage range 2 must be selected on the module for this mode.
Low Level Input Mode
The Low Level input mode (only for channels 1 and 2) detects
differential input voltage. Voltages can range from 50 millivolts
(p-p) to 10 Volts (p-p). Set voltage ranges by routing the inputs
through preamplifiers. Switch the preamplifiers in or out with
slide switches S2 and S3 on the DSM. An input voltage of 25
millivolts or more is a logic one in the module, and a voltage of
less than -25 millivolts is a logic 0. To select this range you also
must select range 2.
The input isolation block has current limiters and optocou-
plers to isolate the sixteen field inputs from the module cir-
cuitry. All inputs pass through high-speed, open collector,
opto-isolators. The input signals go through the Schmitt-trig-
ger inverters to enhance the pulse definition.
Between the opto-isolators and the inverters are RC circuits
that produce an 8.5 millisecond debounce time delay. Connect
jumpers J9 through J16 for the time delay. The input circuits
provide 350 Volts RMS isolation between input and logic cir-
cuits, and 150 Volts RMS isolation between input channels.
The DSM can be divided into functional modules, see Figure
. These modules provide the control functions in the DSM.
MODULE DESCRIPTION
Figure
shows the DSM block diagram to illustrate signal
flow through the module. The input circuits connect to the ter-
mination unit that connects them through the termination
unit cable to the P3 edge connector on the DSM.
