IBM CIO-DIO48H manual Digital I/O Isolation, Unconnected inputs float

CIO-DIO48H User's Guide Functional Details

	+5 VDC	2.2 K SIP	Dot
	HI	COM
	n7
	n6		ConnectorUser LinesI/ODigital
	n5
Digital	n4
I/O
Port	n3
	n2
n = A, B, or C	n1
	n0

LO (GND)

2.2 K SIP installed for pull-up

+5 VDC

		HI	2.2 K SIP
	n7
	n6		ConnectorUser	LinesI/ODigital
	n5
Digital	n4
I/O
Port	n3
	n2
n = A, B, or C	n1
	n0

LO	COM
(GND)	Dot

2.2 K SIP installed for pull-down

Figure 5. Pull-up and pull-down resistor SIPs schematic

To pull-up lines, orient the SIP with the common pin (dot) toward the HI end; to pull-down, install the resistor with the common pin in the LO hole. When installing pull-up and pull-down resistor SIP packs, we recommend 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.

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