SSR-RACK48
48 Channel Solid State Relay (OPTO22, Gordos) Mounting & Interface RackDescription
The SSR-RACK48 is a high-density mounting and interface
rack for use with quad-type solid-state relays. The SSRRACK48 is the perfect means of interfacing quad solidstate relays (SSR) modules to any 48, 96, or 192-line digital
I/O board with 50-pin connectors
SSR-RACK48 provides positions for 12 quad relays, andhas screw terminals for each module. The screw terminals
allow you to connect signals via 12-22 AWG wire. Signals
are routed through the SSRs to the 50-pin, 48-lineconnector.

The SSR-RACK48 is 100% connector-compatible with thefollowing Measurement Computing Corporation (MCC)
boards: PCI-DIO48H
 PCI-DIO48H-RT
 PCI-DIO96H
 CIO-DIO48
 CIO-DIO96
 CIO-DIO192

 CIO-DI48
 CIO-DI96
 CIO-DI192
 CIO-DO48
 CIO-DO96
 CIO-DO192

By using any of these products with the SSR-RACK48, you
can construct a digital control system with the highest
possible density.

DS SSR-RACK48.doc
Document Revision 1.1, March, 2010

Copyright © Measurement Computing Corporation

SSR-RACK48 DatasheetSSR-RACK has on-board buffers

Quad relays required

Because most manufacturers of SSR racks do not supply
output buffers on the SSR rack, simple digital I/O boards
such as the CIO-DIO24, 48, and 96, and othermanufacturer's 82C55-based digital I/O boards do not havethe power to switch the SSRs. For example, to use an
OPTO22 PB16 rack, you need to use a high-drive DIO
board such as the CIO-DIO24H or CIO-DUAL-AC5.

SSRs are available as a single-relay circuit in a plastic case,or as four identical relay circuits in a plastic case. The SSRRACK48 requires quad relays. MCC's SSR-4 series of quad
I/O modules are compatible with the SSR-RACK48.
Because of the savings in racks, cables, and cabinet space,quad relays are the economic alternative to single-function
relays.

In order to be usable with all common TTL output boards,
the SSR-RACK48 is designed with buffers on board. With
these buffers, you can plug directly into the SSR-RACK48
from your CIO-DIO 48, 96 or 192 or any othermanufacturer's 82C55-based digital I/O board.

Quads have shared commons

Choosing solid state relays

SSR-RACK inverting logic

AC or DC, input (sense) or output (switch)

On an input SSR, the presence of a voltage raises the TTL
output of the SSR from TTL low to TTL high. Because theSSR-RACK uses the conventional inverting logic, thecompleted circuit of SSR and SSR-RACK lowers the signal
to the DIO board from TTL high (+5) to TTL low (GND).
An output SSR completes a circuit when the DIO board
TTL signal to the SSR is low. The circuit through the SSR
is open when the signal from the DIO board is high.

An SSR module performs one of the following functions:

AC input
AC output
DC input
DC output

The SSR senses (input) and switches (output) AC and DCvoltages.
4,000 volt AC isolation
The high voltage AC or DC signal never reaches the DIOboard. Instead, the signal is converted to TTL by the SSR(input) or switched by the SSR (output). The DIO board
and the PC are protected from up to 4,000 volts (V) AC on
the SSR's inputs by the optical isolation circuit in the SSR.
Detect and control voltage and current loads thatexceed the capability of TTL

Quad relays are constructed with a shared common between
each pair of two SSR circuits. This may be important,depending on the relay-to-relay isolation required by yourapplication.

Converting the SSR-RACK from inverting logic
The SSR-RACK follows the convention set by OPTO22
and followed by virtually all SSR rack manufacturers — thesense and control logic for the relays is inverted. Thismeans that a 0 output from the digital I/O board causes anoutput relay to activate (complete the circuit), while a 1(TTL high) causes the relay to deactivate. The chips which
invert the logic are socketed and can be easily replaced withchips that do not invert the logic. Discuss your order with atechnical sales engineer if you need non-inverting logic.

SSR modules can switch loads up to 3.5 A at rated voltagesof 280 VAC and 200 VDC (1 A max). A single SSR canstart small motors, switch large capacity motor-starter
relays, electric appliances, sprinkler valves, alarms, andannunciator beacons.

DS SSR-RACK48.doc
Document Revision 1.1, March, 2010

Copyright © Measurement Computing Corporation

SSR-RACK48 Datasheet

I/O connector pin out

Pin map
Refer to the following pin mapping table if your digitalboard is not a Measurement Computing board.
Signal name
FIRSTPORTA Bit 0
FIRSTPORTA Bit 1
FIRSTPORTA Bit 2
FIRSTPORTA Bit 3
FIRSTPORTA Bit 4
FIRSTPORTA Bit 5
FIRSTPORTA Bit 6
FIRSTPORTA Bit 7
FIRSTPORTB Bit 0
FIRSTPORTB Bit 1
FIRSTPORTB Bit 2
FIRSTPORTB Bit 3
FIRSTPORTB Bit 4
FIRSTPORTB Bit 5
FIRSTPORTB Bit 6FIRSTPORTB Bit 7
FIRSTPORTC Bit 0
FIRSTPORTC Bit 1
FIRSTPORTC Bit 2
FIRSTPORTC Bit 3
FIRSTPORTC Bit 4
FIRSTPORTC Bit 5
FIRSTPORTC Bit 6
FIRSTPORTC Bit 7
SECONDPORTA Bit 0
SECONDPORTA Bit 1
SECONDPORTA Bit 2
SECONDPORTA Bit 3
SECONDPORTA Bit 4
SECONDPORTA Bit 5
SECONDPORTA Bit 6
SECONDPORTA Bit 7
SECONDPORTB Bit 0
SECONDPORTB Bit 1
SECONDPORTB Bit 2
SECONDPORTB Bit 3
SECONDPORTB Bit 4
SECONDPORTB Bit 5
SECONDPORTB Bit 6
SECONDPORTB Bit 7
SECONDPORTC Bit 0
SECONDPORTC Bit 1
SECONDPORTC Bit 2
SECONDPORTC Bit 3
SECONDPORTC Bit 4
SECONDPORTC Bit 5
SECONDPORTC Bit 6
SECONDPORTC Bit 7

Pin
Module 1
Module 2
Module 3
Module 4
Module 5
Module 6
Module 7
Module 8
Module 9
Module 10
Module 11
Module 12
Module 13
Module 14
Module 15
Module 16
Module 17
Module 18
Module 19
Module 20
Module 21
Module 22
Module 23
Module 24
Module 25
Module 26
Module 27
Module 28
Module 29
Module 30
Module 31
Module 32
Module 33
Module 34
Module 35
Module 36
Module 37
Module 38
Module 39
Module 40
Module 41
Module 42
Module 43
Module 44
Module 45
Module 46Module 47
Module 48

DS SSR-RACK48.doc
Document Revision 1.1, March, 2010

Copyright © Measurement Computing Corporation