Pulse outputs - old forum post


Joined on 09-08-2008
Posts 8
whether SNAP-OAC5i can satisfy the Operating Mode: Pulse (0.1 - 1.0s), Latch?

I would like to ask what is the meaning of Operating mode: Pulse (0.1-1.0s), Latch?

whether SNAP-OAC5i can satisfy the Operating Mode: Pulse (0.1 - 1.0s), Latch?

many thanks


12-11-2008, 1:58 PM


Joined on 12-01-2003
Optomation Systems, Madrid, Spain
Posts 153
Re: whether SNAP-OAC5i can satisfy the Operating Mode: Pulse (0.1 - 1.0s), Latch?

I presume this is a specification provided by a customer; it doesn’t appear to come from Opto22. Are you referring to the pulse output capability of SNAP modules? There are two factors involved with creating pulses, firstly the hardware specification and secondly the programmable software functionality, in the SNAP product line, provided by the SNAP-PAC brain processor.

From the information available from the digital output specification sheet (1144_SNAP_Digital_Output_Mods_data_sheet) the turn on time for the SNAP-OAC5-I module is 100microseconds (0.0001 seconds) and the turn off time is 750microseconds.(0.00075 seconds) well within your specification for pulse generation. Note that these values are not the same for all SNAP output modules.

PACControl provides a software and hardware platform to create control applications using the SNAP Processor Brains. The following commands are used to create pulse outputs

*Start Continuous Square Wave

*Start On-Pulse

*Start Off-Pulse

*Generate N Pulses

The minimum On Time and Off Time is 0.001 second with a resolution of 0.0001 second making the maximum frequency 500 Hertz. I suggest you read the description of each command to understand the configurable resolution and functionality.

Note that subtle differences in the hardware design of different SNAP Processors also enforce a minimum period independently of the modules being connected or configured software:

*SNAP-PAC-R1 0.006 seconds
*SNAP-PAC-EB1 0.040 seconds
*SNAP-PAC-SB1 0.050 seconds

Latch functionality in PACControl is provided by the commands

*Turn On
*Turn Off
*Start On Pulse
*Start Off Pulse

The turn on/off commands provide the latch functionality. The start pulse commands guarantee that the output will return to a preset state without further programming commands. Don’t forget that the fail safe mode of all optically controlled outputs is OFF. If the equipment loses power all outputs will fail open (0), the only way of changing this is to use a NC external relay, in which case its electrical specification must be considered.

Without having all the details, I would consider that the SNAP-ODC5-I module meets your specified requirement.