S5 to S7 conversion project.

A major paper processing plant experienced problems with an old/outdated S5 PLC system. The system was an S5-95U CPU with a large amount of I/O. The existing system was difficult to troubleshoot and not easy to maintain. Fast Automation was contracted to upgrade the system to a new and serviceable system but at a minimum cost.

Existing System:-
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Existing Rack Components:-

Part No.	Description	Qty
6ES5103-8MA12	SIMATIC S5 CPU 103	1
6ES5470-8MA11	Analog Output Module - 2AO	1
6ES5385-8MA11	Down counter with 2 Channels up to 500Hz	1
6ES5421-8MA12	Digital Input 8x 24V DC	11
6ES5441-8MA11	Digital Output 8x 24V DC 1A	8

At first glance not an obvious choice but the Siemens ET200s was selected as the platform solution. Fast Automation believes the Siemens ET200S IM151-7 CPU is a hard option to look past, for smaller Siemens S5 upgrades.

Summary of ET200s suitability factors:-

Processing power is not a real requirement when upgrading the S5-95U, most modern small PLC’s will outperform it. IF using the ET200s CPU’s
The memory requirement is minimal
The I/O can be selected to match card for card upgrading which minimizes drawing changes.
The footprint is exceptionally small and therefore can usually be mounted alongside the old PLC without the need for existing cabinets.
Spares are readily available, and the system is hot-swappable and low power.

New Rack Components:

Order number	Designation	Quantity
6ES7131-4BF00-0AA0	Electronics module, 8DI, 24 V DC, standard (1 unit)	14
6ES7132-4BF00-0AA0	Electronics module, 8DO, 24 V DC/0.5A, standard (1 unit)	9
6ES7135-4FB01-0AB0	Electronic module, 2AO, U	2
6ES7138-4DE02-0AB0	1 Count 5V/500kHz, connection for RS422 incremental encoders
6ES7138-4CA01-0AA0	PM-E DC 24V power module for electronic modules, with diagn.	1
6ES7151-7AA20-0AB0	IM 151 – 7 CPU	1
6ES7193-4CA40-0AA0	Universal terminal module; screw connection (5 pcs.)	5
6ES7193-4CD20-0AA0	Terminal module for AUX1 supply; screw connection	3

New Rack Image:

The difficulty with upgrading S5 to S7 is often that the machine needs to maintain it’s operation throughout the upgrade or have a limited downtime. One technique Fast Automation has developed for minimizing the downtime is to utilize plug in terminals as shown below:-

The process can be divided into the following steps:
Step 1: The existing PLC is prewired to go through these small plug terminals, and tested/left in production.
Step 2: The new PLC is then prewired with plugs to suit.
Step 3: The new PLC is mounted ready for cutover.
Step 4: Cutover, the old PLC is unplugged the new PLC is plugged in, tested and production continues safe that if any issue is encountered a rollback can be performed in minutes.

Picture of old PLC unplugged while the new PLC is trialed (Please note: aesthetics aren’t so important during this temporary trial period):-

Step 5: After a period of testing and “comfort” the old plc is removed at a convenient time.
Below is a picture of the removed PLC (including plug in connectors) from this project.

The before and after shots:-
Before:
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After:
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The project was executed without downtime and in cutover execution, a rollback was not required. However, the option (to rollback), reduced the pressure on everyone and helped facilitate a relaxed productive commissioning phase.

For further information please contact Fast Automation’s David Askew 0418 239 340 or email info@fast-automation.com