Measurement Computing USB-SSR08, User Manual

Chapter 4 

Specifications 

Typical for 25 °C unless otherwise specified.  
Specifications in 

italic text

 are guaranteed by design. 

I/O module configuration 

Table 1. I/O module configuration specifications 

Modules 1-4

User-selectable via switch S1 "CL" position as either input modules or output (default) 
modules. Switch settings for direction can be read back via software. Do not mix input 
and output modules within this bank of four.

Modules 5-8

User-selectable via switch S1 "CH" position as either input modules or output (default) 
modules. Switch settings for direction can be read back via software. Do not mix input 
and output modules within this bank of four.

Pull-up/pull-down on digital 
I/O lines 

Configurable via switch S3 with 2.2 K ohm resistor network. Switch settings for pull-
up/pull-down selection can be read back via software. Default to pull-up. Switch 
settings are applicable during power up conditions of output modules only. Modules are 
active Low. When switch to Pull-up, modules are inactive on power up. When switched 
to pull-down, modules are active on power up. 

I/O module logic polarity 

Selectable via switch S2. Switch settings for polarity can be read back via software. 
Default to non-inverted. For input modules, invert mode returns a “1” when module is 
active; non-invert mode returns a “0” when module is active. For output modules, 
invert mode allows users to write a "1" to activate the module; non-invert mode allows 
users to write a "0" to activate the module. 

Power 

Table 2. Power specifications 

Parameter Conditions 

Specification 

USB +5 V input voltage range.    

4.75 V min. to 5.25 V max. 

USB +5 V supply current 

All modes of operation 

<100 mA  

External power supply  
(included) 

MCC p/n CB-PWR-9 

9 V ± 10% @ 1.0 A 

6.0 V > V

ext

 > 12.5 V 

PWR LED = Off (power fault) 

Voltage supervisor limits - 
PWR LED 

6.0 V < V

ext

 < 12.5 V 

PWR LED = On 

All modules off, 0 A downstream hub power 

180 mA typ, 220 mA max. 

External power consumption 

All modules on, 100 mA downstream hub 
power 

300 mA typ, 360 mA max. 

External power input 

Table 3. External power input specifications 

Parameter Conditions 

Specification 

External power input 

+6.0 VDC to 12.5 VDC (9 
VDC power supply included) 

6.0 V > Vext or Vext > 12.5 V 

PWR LED = Off (power 
fault) 

Voltage supervisor limits - PWR LED. 
(Note 1) 

6.0 V < Vext < 12.5 V 

PWR LED = On 

External power adapter (included) 

MCC p/n CB-PWR-9

+9 V ±10%, @ 1.0 A

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