Todays deals on Instruments Siemens?

TEXAS INSTRUMENTS 5110-10 USPP 511010 $8,422.60

TEXAS INSTRUMENTS 575-2103 NSFP 5752103 $7,776.30

TEXAS INSTRUMENTS 575-2105 USPP 5752105 $6,541.20

TEXAS INSTRUMENTS 565-2820 NSFP 5652820 $6,236.45

Siemens and Texas Instruments lot Rack used nice shape all other items new $6,000.00

TEXAS INSTRUMENTS 560-2125 USPP 5602125 $5,793.70

TEXAS INSTRUMENTS 560-2124 NSFP 5602124 $5,748.85

TEXAS INSTRUMENTS 555-1104 USPP 5551104 $5,406.15

TEXAS INSTRUMENTS 555-1106 USPP 5551106 $5,345.20

TEXAS INSTRUMENTS 565-2820 NSPP 5652820 $4,988.70

TEXAS INSTRUMENTS 575-2103 USPP 5752103 $4,861.05

TEXAS INSTRUMENTS 555-1101 NSPP 5551101 $4,779.40

TEXAS INSTRUMENTS 505-ATM-4120 USPP 505ATM4120 $4,257.30

TEXAS INSTRUMENTS 530T-1112 NSFP 530T1112 $4,005.45

TEXAS INSTRUMENTS 6EA1710-0AA00-2AA1 USPP 6EA17100AA002AA1 $3,950.25

TEXAS INSTRUMENTS VPU210-3105 USPP VPU2103105 $3,896.20

TEXAS INSTRUMENTS 575-2104 USPP 5752104 $3,881.25

TEXAS INSTRUMENTS 505-2556 USPP 5052556 $3,804.20

TEXAS INSTRUMENTS 560-2820 NSFP 5602820 $3,788.10

TEXAS INSTRUMENTS 565-2820 USPP 5652820 $3,742.10

TEXAS INSTRUMENTS PFS-3611 USPP PFS3611 $3,662.75

Siemens Texas Instruments 555-1105 PLC $3,600.00

TEXAS INSTRUMENTS 530-1102 NSFP 5301102 $3,567.30

TEXAS INSTRUMENTS 560-2820 NSPP 5602820 $3,473.00

TEXAS INSTRUMENTS 500-3103 USPP 5003103 $3,467.25

TEXAS INSTRUMENTS 560-2124 USPP 5602124 $3,448.85

TEXAS INSTRUMENTS 555-1101 USPP 5551101 $3,439.65

TEXAS INSTRUMENTS 505-ATM-0440 NSPP 505ATM0440 $3,383.30

TEXAS INSTRUMENTS MON-4614-SM NSFP MON4614SM $3,381.00

TEXAS INSTRUMENTS 560-2120W NSFP 5602120W $3,381.00

TEXAS INSTRUMENTS 530T-1112 USPP 530T1112 $3,338.45

TEXAS INSTRUMENTS 505-5103 NSFP 5055103 $3,320.05

TEXAS INSTRUMENTS 500-5186 NSPP 5005186 $3,156.75

TEXAS INSTRUMENTS 555-1103 NSPP 5551103 $3,115.35

TEXAS INSTRUMENTS 535-1212 USPP 5351212 $2,932.50

TEXAS INSTRUMENTS 505-ATM-0440 USPP 505ATM0440 $2,919.85

TEXAS INSTRUMENTS 555-1103 USPP 5551103 $2,832.45

TEXAS INSTRUMENTS PFS-3607 USPP PFS3607 $2,826.70

TEXAS INSTRUMENTS 560-2128 NSPP 5602128 $2,802.55

TEXAS INSTRUMENTS 500-5053 NSPP 5005053 $2,795.65

TEXAS INSTRUMENTS 560-2123 NSFP 5602123 $2,791.05

Siemens / TI 575-2103 CPU Module VME PLC Texas Instruments 5752103 $2,750.00

TEXAS INSTRUMENTS 555-1105 NSPP 5551105 $2,704.80

TEXAS INSTRUMENTS 5120-11 USPP 512011 $2,688.70

TEXAS INSTRUMENTS PC405-6201 NSFP PC4056201 $2,655.35

TEXAS INSTRUMENTS 505-ATM-0220 USPP 505ATM0220 $2,643.85

TEXAS INSTRUMENTS 505-2557 NSFP 5052557 $2,639.25

TEXAS INSTRUMENTS 500-5023 NSFP 5005023 $2,632.35

TEXAS INSTRUMENTS 5TI-1020-1 USPP 5TI10201 $2,622.00

TEXAS INSTRUMENTS VPU500-3104 USPP VPU5003104 $2,587.50

TEXAS INSTRUMENTS 500-7203 USPP 5007203 $2,587.50

TEXAS INSTRUMENTS 500-7204 USPP 5007204 $2,587.50

TEXAS INSTRUMENTS 560-2128 USPP 5602128 $2,547.25

TEXAS INSTRUMENTS 500-5053 USPP 5005053 $2,541.50

TEXAS INSTRUMENTS CVU-TIWAY-ADAPTER-CARD-FOR-PC NSPP CVUTIWAYADAPTERC $2,530.00

TEXAS INSTRUMENTS SERIES 500 PLC, 520C-1102 $2,500.00

TEXAS INSTRUMENTS RTU-8635-SSD NSFP RTU8635SSD $2,484.00

New in Box 530T-1112 Siemens/Texas Instruments TI PLC Processor 530T1112 N787 $2,499.00

TEXAS INSTRUMENTS 555-1105 USPP 5551105 $2,479.40

TEXAS INSTRUMENTS 560-2820 USPP 5602820 $2,472.50

TEXAS INSTRUMENTS 500-7201 USPP 5007201 $2,458.70

TEXAS INSTRUMENTS PC-505-6201 NSFP PC5056201 $2,415.00

TEXAS INSTRUMENTS 2600555 USPP 2600555 $2,415.00

TEXAS INSTRUMENTS 500-5023 NSPP 5005023 $2,413.85

TEXAS INSTRUMENTS 500-5047A NSFP 5005047A $2,401.20

TEXAS INSTRUMENTS 575-6663 USPP 5756663 $2,337.95

TEXAS INSTRUMENTS 560-2123 USPP 5602123 $2,326.45

Texas Instruments 500 System PLC Series Rack 13 Modules $2,295.95

TEXAS INSTRUMENTS 500-5035 NSFP 5005035 $2,301.15

TEXAS INSTRUMENTS 500-5038 USPP 5005038 $2,294.25

TEXAS INSTRUMENTS 500-7102 USPP 5007102 $2,289.65

TEXAS INSTRUMENTS 555-1102 USPP 5551102 $2,257.45

New in Box 555-1105 Texas Instruments Siemens TI PLC 5551105 N14 $2,249.00

TEXAS INSTRUMENTS 560-2120W USPP 5602120W $2,185.00

TEXAS INSTRUMENTS 2459322 NSFP 2459322 $2,182.70

TEXAS INSTRUMENTS 560-2132 NSFP 5602132 $2,145.90

TEXAS INSTRUMENTS 505-CP2572 NSPP 505CP2572 $2,116.00

TEXAS INSTRUMENTS PM550-112 USPP PM550112 $2,116.00

TEXAS INSTRUMENTS 505-CP1434TF NSFP 505CP1434TF $2,083.80

TEXAS INSTRUMENTS RTU-8635-SSD USPP RTU8635SSD $2,070.00

TEXAS INSTRUMENTS 500-2114A NSFP 5002114A $2,025.15

TEXAS INSTRUMENTS PM550-C-112 USPP PM550C112 $2,012.50

TEXAS INSTRUMENTS PWB-2599168-0001 USPP PWB25991680001 $2,012.50

TEXAS INSTRUMENTS 5TI-1013 USPP 5TI1013 $2,012.50

TEXAS INSTRUMENTS 2223050-0003 USPP 22230500003 $2,012.50

TEXAS INSTRUMENTS 2223050-0004 USPP 22230500004 $2,012.50

Texas Instruments 500 System PLC Series Rack 11 Modules $1,995.00

TEXAS INSTRUMENTS 5TI-1021-1 USPP 5TI10211 $1,983.75

555-1105 Texas Instruments Simatic PLC TI555 TI 5551105 N60 $1,999.00

TEXAS INSTRUMENTS 560-2130 NSPP 5602130 $1,967.65

TEXAS INSTRUMENTS 500-5047A NSPP 5005047A $1,964.20

TEXAS INSTRUMENTS 505-CP2572 USPP 505CP2572 $1,923.95

TEXAS INSTRUMENTS 560-2126 NSFP 5602126 $1,910.15

TEXAS INSTRUMENTS 505-CP1434TF NSPP 505CP1434TF $1,910.15

TEXAS INSTRUMENTS 560-2126B NSFP 5602126B $1,910.15

SIEMENS TEXAS INSTRUMENTS MONITOR CVU100 $1,850.00

SIEMENS TEXAS INSTRUMENTS MONITOR CVU100 $1,850.00

TEXAS INSTRUMENTS 2490092 USPP 2490092 $1,895.20

TEXAS INSTRUMENTS UNILINK NETWORK ADAPTER 500-7111 $1,895.00

TEXAS INSTRUMENTS 7MT-700 NSFP 7MT700 $1,845.75

Instruments Siemens Questions

Integrated Safety Instrumented Systems and Distributed Control Systems – Are They a Good Idea?

For those of you who have been entrusted with the task of selecting a safety instrumented system for use in your plant, often run into a perplexing question. Should I go for an integrated Safety Instrumented System, which will be totally different from my Distributed Control system (or DCS for short)? Or should I select one of the newer “integrated systems”, that comprise of both the Distributed Control System and a Safety Instrumented System in one package?

A Safety Instrumented System (or SIS) is a special kind of control system that is used for the safety critical parts of process plants, turbo machinery, boilers and other machinery or equipment that has to be controlled with a very high degree of reliability in order to run it safely, as well as bring it to a safe state if something goes wrong. Emergency Shutdown Systems (ESD for short), can be considered a subset of the SIS category of control systems.

On the other hand DCS (Distributed Control Systems) are those control systems that are used for normal control and monitoring operations of process plants, oil refineries, oil & gas production platforms, power plants and so on. The DCS is the main system that measures, monitors and controls various process parameters like flow, temperature, pressure and so on. In standards related literature, this system is also referred to as the BPCS (short for Basic Process Control System).

In the view of the standards bodies (like IEC and ISA), these two systems have to be completely separate, as these safety instrumented systems have to be dedicated to controlling only the safety critical parts of the plant .The ordinary DCS cannot be said to be robust, fail-safe and sure to operate the safety critical instruments at all times. This distinction between the DCS and SIS, led to separate markets for both types of systems with separate suppliers for both, initially. Thus companies like Triconex, HIMA, Pilz and ICS Triplex were the traditional vendors of these Safety Instrumented Systems, whereas the BPCS or DCS market belonged to the companies like Emerson, ABB, Honeywell, Yokogawa and Invensys.

This obviously, meant that now, if a plant had instruments and controls that were designated as safety critical, it necessarily required a separate SIS; the DCS would not do at all because of what the standards state. Thus now, one control room had two control systems, completely different as chalk and cheese. The SIS had separate power supply (or a UPS), separate panels, monitoring stations, separate programming software and of course totally separate hardware from the DCS. The same Instrument engineer who maintained the instruments and controls of this process plant, now had to be adept at both systems simultaneously. Plant modifications and changes were a pain as any change had to be implemented in both systems, with a lot of testing to ensure that the original interlocks and loops worked as designed to.

Making the two systems communicate with each other, also proved not so simple, since even after DCS vendors had come out with open systems, the Safety Instrumented System vendors were reluctant to migrate to such systems, due to the extensive proof testing required to ensure that the “open” systems were bug free.

Hence, most instrument engineers in these situations started wishing for a new deal, whereby both the SIS and the DCS could talk to each other seamlessly (even while remaining separate to conform to the standards) . Also, what if they could share a common engineering /programming platform as well? That would be the icing on the cake!

The DCS vendors sensed this mood of the users and many of them came out with “integrated” DCS/SIS systems, where the DCS and SIS controllers are different, but part of the same overall system. Some recent examples are Emerson’s Delta V with SIS and Siemens Safety Integrated system. These reportedly have become popular, due to the fact that most of these integrated systems have got third party (most commonly TUV) certificates for the SIS part, so users can have a worry free installation of these for safety critical applications. However, I have not yet seen any debate in the technical media, regarding this issue. Are these systems doing great, or are users now longing for the earlier separate DCS/SIS systems? I think we need some more time and more data, to arrive at any definitive conclusion. The advantages of an integrated DCS/SIS are obvious, as stated above. The disadvantages are somewhat less obvious. One disadvantage is that if the SIS portion is really easy to program, then there is a chance that unauthorized users (say a savvy DCS operator) might end up changing protected settings like interlock bypasses and setpoints, which is really dangerous. Plus the thought of having an SIS with a standard “open” OS like Windows, is rather uncomfortable, as the last thing one wants is a system freeze during an emergency.

Only time will tell, if the integrated SIS/DCS systems were a better choice than the stand-alone SIS, as then we would have enough data to have a balanced view.

About the Author

Samuel P. Whittle is a technical expert working with Abhisam Software. His interests include
Safety Instrumented Systems
and their design. He has worked with a number of
SIS
as well as integrated
DCS SIS architectures
.The views expressed here are his own.

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