Spectrum Controls 1771sc-IFE32 - Manual (Page 33)

Chapter 4: Configuring Your Module 23
requests for data until the sample time period elapses. If the sample period elapses
and no BTR requests have occurred since the interval started, the RTS bit is flagged
indicating an RTS synchronization error.
Word/Bit 15 14 13 12 11 10 09 08 07 06 05 04 03 02 01 00 Group
23 Real Time Sampling RTS
RTS is invaluable for time based functions (such as PID and totalization) in the PLC. It
allows accurate time based calculations in local or remote I/O racks. In the RTS mode
the module scans and updates its inputs at a user defined time interval (T) instead of
the default interval. The module ignores block transfer read (BTR) requests for data
until the sample time period elapses. The BTR of a particular data set occurs only
once at the end of the sample period and subsequent requests for transferred data
are ignored by the module until a new data set is available. If a BTR does not occur
before the end of the next RTS period, a time-out bit is set in the BTR status area.
When set, this bit indicates that at least one data set was not transferred to the
processor. (The actual number of data sets missed is unknown.) The time-out bit is
reset at the completion of the BTR.
Set appropriate bits in the BTW data file to enable the RTS mode. You can select RTS
periods ranging from 100 milliseconds (ms) to 3.1 seconds. Refer to the table below
for actual bit settings. Note that the default mode of operation is implemented by
placing all zeroes in bits 0–15.
The real time sampling (RTS) mode of operation provides data at a precisely gathered
time interval. The RTS bit is defined in the diagnostics byte in the BTR map.
Bit settings for real time sample mode:
RTS: Sample Time: RTS: Sample Time:
0* Disabled 16 1.6 s
1 100 ms 17 1.7 s
2 200 ms 18 1.8 s
3 300 ms 19 1.9 s
4 400 ms 20 2.0 s
55 00 ms 21 2.1 s
6 600 ms 22 2.2 s
7 700 ms 23 2.3 s
8 800 ms 24 2.4 s
9 900 ms 252.5 s
10 1.0 s 26 2.6 s
11 1.1 s 27 2.7 s
12 1.2 s 28 2.8 s
13 1.3 s 29 2.9 s
14 1.4 s 30 3.0 s
151.5 s 31 3.1 s
Scaling: Scaling: Scaling: Scaling: Scaling:
The user may define Scaling to be applied to the input data by defining a 16 bit word
value for the minimum full scale reading and a 16 bit word value for the maximum full
scale reading. The module will apply linear equations to the values sampled such that
values sampled at the range end points are represented as equivalent to the user
defined min/max scaling for a given channel. If both the min and max scale values are