Remote Processing RPC-2300 - Manual (Page 19)

CHAPTER 6 DIGITAL LINES
RPC-2300 Page 17
Figure 6-2 Inductive load protection
a 1 is writte n to the high cur rent por t, the o utput is
switched on and goes low.
The output driver chip, U 20, can be replaced w ith a DIP
shunt jumper so it is like the other lines at J3.
NOTE: Outputs at the high current lines are not
compa tible with TT L logic leve ls and should
not be used to drive other logic devices.
Each of the high current outputs can sink 100 ma at 50V.
WARNING:
External supplies using the high cu rrent outputs m ust
be tied to J3, pin 26 and NOT the power connector.
Failure to do so can produce a ground loop and
cause erratic operation.
The thermal time constant of U20 is very short, so the
numbe r of outputs th at are on a t any one tim e should
include those that overlap even for a few milliseconds.
Incandesc ent lamps h ave a " cold" c urre nt of 11 times its
o p er a ti ng c ur r e nt . L a m ps r eq u ir i ng m o re th a n 5 0 m a
should not be used.
Protection diodes m ust be used with inductive loads.
Refer to figure 6-2
Do not pa rallel outputs f or higher drive. This could
result in damage since outputs do not share current
equally.
Interfacing to an opto-module rack
J2 and J3 I/O lines interface to an MPS-8, 16, or 24
position opto m odule rac k. L ines not going to an opto
module connect to a screw terminal on the MPS-XX
series boards. This feature allows you to connect
s w it ch e s o r ot he r T T L t yp e de v ic e s t o t he d ig it al I/ O
lines. The MPS-XX series boards accept G4 series
modules.
Use the O PTO comm and to acces s and contr ol G4 opto
modules. The LIN E comm and is used to access
individual lines on the STB-26 or MPS-X X rack.
A CM A-26 connects J2 and J3 on the SBS-2300 to the
MPS-XX board. Cable length should be less than 2 feet
for the 8 position rack and 18 inches for the 16 and 24
positions. Excessive cable lengths cause a high voltage
drop an d conseque ntly unreliab le opera tion. Be su re to
supply + 5V and ground to the appropriately marked
terminals.
You must configure the 8255 ports for outputs before
using them. Use the following table to determine the
corr esponding op to channel for a particula r 82C 55 port:
Opto 82C55 Connector Addr.
channels port
M 0 -M 3 Lower C J2 2
M 4 -M 7 Upper C J2 2
M8-M 15 A J2 0
M16-M 23 B J2 1
M100-M 103 Lower C J3 66
M104-M 107 Upper C J3 66
M108-M 115 A J3 64
M116-M 123 B J3 65
"Opto channel" is the position as marked on the MP S-xx
board. The channel number is preceded by a ' M'
character on the MPS board. W hen connecting J3 to an
opto rack, add 100 to the number on the rack. J3 has a
high current output on port A (channels M8-M 15).
Replace U20 with a shunt jumper to operate norm ally.
To turn on an opto module, an output line must be low.
A mod ule is turned off by wr iting a ' 1' to a channel.
The logic a t J3 port A , w ith the high cur rent outpu ts
installed is just the reverse. A ' 1' at a line causes the
m o d ul e t o t ur n O N .