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Calibration is comparing the instrument's reading to a reading when a pressure standard is applied. Whether a late model smart pressure transmitter needs calibration when changing the range is up to corporate policy. Having talked with others about what their policies are, those that require...

Ken, Firefox now finds normal words like modbus, cable, wire (although it balked this morning). But the engine still has problems with 3 letter acronyms (maybe it always did?) It can't find 485 or RTU or rtu or CPU or TIA or UDC or CDA or I/O or PLC or P/S It finds 4 character...

I think it might have broken the site search engine. The search results for RS-485, Modbus and shielded each returned zero hits.

solution posted here: http://www.plctalk.net/qanda/showthread.php?t=116197

I use a specific brand and model serial server (485/Ethernet) even though I hate the non-removeable wiring terminals because it has blinking LEDs that have proven to valuable in getting the serial side operational. There's a number of issues that make 485 more troublesome than Ethernet, and...

Is a software package for setup common? Not really. There are other Modbus field instruments that use a firmware/Modbus-writeable slave ID address, but those I've dealt with use a single slave ID register where you can write an interger value to the default slave ID register address and...

Yes, you will have to change the slave node ID address so each node has a unique, individual node ID address. Sometimes that is done with DIP/rotary switches or jumpers, other times it's done in firmware setup. You might not have to power cycle the slave after cable installation, but many...

I didn't do an engineering evaluation of the other cables you suggested. I just want to let you know that I've used STP CAT6 for RS-485 at 38K baud at 100m distances several times and the CAT6 worked and has continued to work fine. As to the effect of using 120 ohm termination resistors, I...

Yes, it's possible. Both Modscan32 and Modpoll are generic Windows Modbus master/clients. So if you can read data from a Modbus slave/server using Modscan32, you should be able to read the same data using Modpoll. If the comm link is RS-232 or RS-485, then either will likely use a USB/RS-xxx...

1. hexadecimal No, hexadecimal is just for us humans to more readily identify a string of bits. Machines use binary, ones and zeroes. So, technically, the Modbus (and HART, Foundation Fieldbus, Profibus and all the other) message is binary. But it is really hard for me to talk to you about...

If I had STP CAT6, I'd use it. I have in the past and it works great. Use a 'pair' as a single conductor to provide a lower conductor resistance. With four pair in the cable, you've even got a pair available for a signal ground connection. The extra conductors would not be used...

Bela Liptak's Instrument Engineering Handbook, Process Measurement and Analysis, Vol 1, has a description of the use a DP pressure transmitter on a level bubbler that employs impulse tubing in a configuration to allow the liquid to boil to its vapor phase, which is what the DP's high side...

The Modbus Specs are of more value for those who are writing firmware/software Modbus code, but you'll need to implement Modbus between different vendors' devices, so for what you're doing I'd recommend - Chipkin's Modbus for Field Technicians...

A low flow at a pressure just higher than the pressure at the end of the site pipe (presumably the combustion chamber) should keep the optics clean. I would take a different approach to your high volume flow rate and use a constant flow regulator to stream a relatively low flow against...

It depends. If the address is a Holding register address then it is in the (4)xxxxx Holding Register memory area. If the address is a Input register address then it is in the (3)xxxxx Input Register memory area. The leading numerals (3) or (4) are not part of the Modbus message, but are...

A friend inherited his Dad's process instrument field calibration business and his Dad's notebook. The notebook lists locations of "Cold Junction" reference points for various plants, building or units, for instance, NW corner of the rolling mill, 6 feet west, 3 feet south, 4 feet deep, 54...

What your DCS guy is asking for a very logical - the DCS is the Modbus (or OPC client) master which means the field device, the SmartAir Lite needs to be a Modbus slave. Modbus slave's each have a unique slave node address (1 through 247). The baud rate and parity need to match the DCS serial...

See the Doric 400 user's manual here: http://www.advindsys.com/Manuals.htm The 400 appears to use sensor specific hardware, as shown on page 2-5, an LSI chip and programming module. Every industrial device I ever seen has a model with configuration and options codes. How Doric...

The Doric series 400 manual at this URL: https://intertechnology.com/Doric/pdfs/400_Series.pdf shows each model has an 'order code', a 3-xx code, that defines that unit's functionality. For instance, the K type T/C indicator is 3-01. The 4-20mA input indicator is 3-61. Is your device...

FYI ASCO solenoid valves have I/S models http://www.lesman.com/acatalog/ASCO_Valve_WBIS_Intrinsically-Safe_Solenoid_Valves.html or EX models http://www.lesman.com/acatalog/ASCO_8210_Explosion-Proof_Normally_Closed.html