Digital I/O Isolation - Measurement Computing CIO-DIO48H User Manual

CIO-DIO48H User's Guide
Digital
I/O
Port
n = A, B, or C
2.2 K SIP installed for pull-up
To pull-up lines, orient the SIP with the common pin (dot) toward the
with the common pin in the
using 2.2K, eight-resistor Single Inline Packages (MCC part number SP-K2.29C). Use a different value only if
necessary.
Unconnected inputs float
Unconnected inputs typically float high, but not reliably. If you are using a CIO-DIO48H for input and have
unconnected inputs, ignore the data from those lines. You do not have to terminate input lines. Unconnected
lines will not affect the performance of connected lines. Mask out any unconnected bits in software.

Digital I/O Isolation

To provide external signal conditioning and isolation, you can connect the CIO-DIO48H to a CIO-ERB24 or
SSR-RACK24. The CIO-ERB24 provides 24 Form C electromechanical relays. The SSR-RACK24 is a
mounting rack for 24 solid-state relays.
The CIO-DIO48H provides digital I/O in groups of 48 bits. Many relay and solid-state relay (SSR) racks
provide only 24-bits of digital I/O. You can configure the CIO-ERB24 relay output board and SSR-RACK24
I/O module rack in a daisy chain configuration to use all of the digital I/O bits provided by the CIO-DIO48H
board. An example of the daisy chain configuration scheme for each board is shown on page 15.
+5 VDC
Dot
2.2 K SIP
COM
HI
n7
n6
n5
n4
n3
n2
n1
n0
LO
(GND)
Figure 5. Pull-up and pull-down resistor SIPs schematic
hole. When installing pull-up and pull-down resistor SIP packs, we recommend
LO
+5 VDC
HI
n7
n6
n5
Digital
n4
I/O
Port
n3
n2
n = A, B, or C
n1
n0
LO
(GND)
2.2 K SIP installed for pull-down
end; to pull-down, install the resistor
HI
14
Functional Details
2.2 K SIP
COM
Dot