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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

5 500 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 25 2.5 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

15 1.5 s 31 3.1 s

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

1 2 ... 28 29 30 31 32 33 34 35 36 37 38 ... 49 50

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