Unexpected count value read from SNAP-SCM-SSI

Applies To:

SNAP-PAC-EB1
SNAP-PAC-EB2
SNAP-PAC-EB1-W
SNAP-PAC-EB2-W
SNAP-PAC-SB1
SNAP-PAC-SB2

Versions Affected:

Problem was discovered in version: R9.2c
Problem is fixed in version: R9.3b

Resolved In Version:

Problem is fixed in version: R9.3b

Symptoms:

The count values read from a SNAP-SCM-SSI module by a SNAP PAC brain may be outside of the expected count range based on the type of encoder used in an application.

Example:

A 14-bit encoder should return count values from 0 to 16383 counts when read by a SNAP PAC brain and a SNAP-SCM-SSI module. Instead, count values of 0 - 16777215 are returned.

Workaround:

With the PAC Control Strategy running, from PAC Control or PAC Manager, divide the counts returned for the SNAP-SCM-SSI input point by the difference of the Data Bits in Data Frame field from 24.

Example: A 14-bit encoder is used with no error bits in the data frame. When configuring the SNAP-SCM-SSI module in PAC Manager, enter 14 in the Data Bits in Data Frame field.

With the returned value from PAC Manager or PAC Control, calculate the correct counts with this formula:

Corrected Counts = Counts / (24 bits - 14 bits)

Where Counts is the count value seen in PAC Manager or PAC Control.

Questions?

Contact: Opto 22 Product Support.
Phone: 800-835-6786 or 951-695-3080
Email: support@opto22.com

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