dchartier

Hello Oswald;
I have no doubt that you could get better performance from the CPU 319-3PN/DP that the S5-155U CPUs you asked about.
Although the S5-155U was considered very high-end processors of their generation, technology has evolved much in nthe past 20 years and newer generation CPUs are faster, more powerful, and have much larger memory potential.
Compare the performance details for the CPU 946/947 (extracted from the manual suggested earlier):

CPU 946/947 Product Summary
Performance features

In the S5-155U programmable controller the CPU 9461947 can be used in single and in multiprocessor mode. It is designed for fast processing of all STEP 5 operations.
With a maximum of 896 kbytes this CPU offers a large memory capacity.
The most outstanding features are:
· Max. 896 kbyte memory for data and user programs, as RAM and for EPROM.
·128 kbyte RAMS are already integrated in the CPU.
· 2048 flags
· 32768 S flags - 256 timers - 256 counters

Processing from up to 4096 binary inputs/ outputs each, 192 analog inputs/ outputs each.
Via special interface modules up to 520 000 digital inputs/outputs each or 32 000 analog inputs/outputs each is possible.
Programming language and program processingUse the STEP 5 programming language to program the CPU 9461947. The types of representation for STEP 5 are the ladder diagram (LAD), control system flow chart (CSF) and statement list (STL). Furthermore GRAPH 5 is available which is used to program sequential controls (step sequences).
The CPU 9461947 allows user programs which are cyclic, alarrn-controlled, time-controlled (max. 9 clock grids). A hardware clock is also integrated.

The average processing time of 1 K instructions is
- 1.4 ms for binary instmctions,
- 1.7 ms for command mix (60 % bits, 40 % words)

and the technical data for the319-3, at the lower end of this link from the Siemens Interactive Catalog:
https://eb.automation.siemens.com/goos/catalog/Pages/ProductData.aspx?nodeID=10034909&catalogRegion=ww&language=en&regionUrl=%2f#B&activetab=product&

Hope this helps,
Daniel Chartier