Casio GR8900a-1 G-Shock Review

This G-Shock GR8900a-1 watch is a robust and heavy looking watch, but in actual fact it is quite light in weight. But it is still extremely sturdy and if you want this as a sports

GR8900a-1 watch them it is certainly up to the task. It looks great both on and off the wrist, and it is surprisingly comfortable too.

G-Shock watches are known for their functionality, and the GR8900a-1 is certainly no exception to that. It has some great features and they are all easy to use and access. This model has a new design, and gives you a multi dimensional look which adds to the character of the watch.

Of course, as with all G-Shock watches, the GR8900a-1 is shock resistant. So if you do want it for wearing while you go about your sports or activities then you can wear this in confidence that it will stand up to anything you put it through.

The GR8900a-1 also has a very bright LED light, that can actually be used for reading a book with. Also handy if you are camping out at night, or on a night walk and you need to read a map as it will provide ample light for you to be able to read from.

A closer look at the GR8900a-1 G-Shock

Solar powered

You may wonder how this watch keeps the bright LED light and the power hungry functionalities of the GR8900a-1 all juiced up. Well, it runs off solar power, and is extremely effective in harnessing the power of the sun and turning it into long lasting power to run the watch.

Even when being used to its full extent, with the light and functions all being used at time, you will still get a lot of life out of this. And it will continue to stay charged as long as you are outside in the light. This is a great way to keep this watch running to its optimal levels at all times.

The GR8900a-1 also uses a power save method. When the watch is left in the dark it will go blank so that no unnecessary power is wasted. If the power does get low on the watch, then there is a power indicator that will let you know that it needs charging so you can get it into the light.

World time

If you travel a lot, you will not have to worry about what the time is in other countries. The GR8900a-1 has 31 built in time zones, covering 48 worldwide cities. You can also turn your daylight saving on or off, depending on where you are. So when you land in a different country you just need to change it to the right time zone and it will automatically set the watch to the right time for you.



The stopwatch on the GR8900a-1 uses 1/100 seconds so you get the most accurate times for your training or events you are at. You also have different measuring modes which include split times, elapsed times and then 1st and 2nd place times. These different modes will allow you to use the stopwatch more effectively in different situations.

Additional information

If you like to have an alarm on your watch, you will be pleased to hear that the GR8900a-1 has 5 different daily alarms that can be used. Set these up with different tones so you can associate a certain tone with a particular event or meeting you have.

There is a countdown timer on the watch too. You can set this to countdown from up to 24 hours. It will count down in 1 second intervals. The GR8900a-1 also has an hourly signal if you like to use one of these. If not, you can simply turn this off.

Final thoughts on the G-Shock GR8900a-1

This watch looks great, with the multi level face and the robust build of the watch. As usual with G-Shock watches, you get a lot of functionality, and this model has a really powerful LED light that can be used for reading. Overall the G-Shock GR8900a-1 is a great quality watch and also really good value for money at the price it is being sold for.


  • Hourly Time Signal
  • Auto-Calendar
  • Module 3285
  • Approx. Battery Life Approx. 3 Years
  • Battery CR2016
  • Tones Button operation tone on/off
  • Backlight Auto LED Backlight (Super Illuminator) with Afterglow
  • Water Resistant Up to 200M Water Resistant
  • Accuracy +/- 15 seconds per month
  • Alarm 5 Independent Daily Alarms (One-time or Daily)
  • World Time
  • Flash Alert
  • Stopwatch 1/100 Second Stopwatch
  • Shock Resistant

Highway Addresable Remote Transducer (HART)

Frequency Shift Keying

Frequency Shift Keying (Photo credit: Wikipedia)

Highway Addresable Remote Transducer (HART) yang kalau diterjemahkan secara bebas menjadi “device yang jauh letaknya namun dengan alamat yang jelas melalui jalan bebas hambatan dapat mengubah suatu besaran fisis menjadi besaran fisis yang lain”. Terjemahan di atas mungkin terasa kacau dan kurang menunjukkan arti sebenernya dari teknologi HART. HART merupakan protocol komunikasi yang dikembangkan oleh HART Foundation. Kalo anda pernah dengar tentang Ethernet maka itu adalah protokol komunikasi yang dikembangkan XEROX. Juga kalau anda pernah dengar Modbus maka itu adalah protokol komunikasi yang dikembangkan oleh Modicon. Dalam perkembangan teknologi instrumentasi dan kontrol, HART merupakan teknology Hybrid yang menjadi transisi antara teknologi konvensional analog dengan teknologi fieldbus.

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Flow Measurements

Ada macam2 metode pengukuran aliran dari uap air, air, minyak, gas, udara, dll. Biasanya pengukuran menggunakan alat dengan tipe DP ( Delta Pressure) atau mengukur melalui perbedaan tekanan.

Ada macam-macam alat pengukur beda tekanan :

1. Orifice Plate
OrificeOrifice Plate
Orifice Plate merupakan alat yang paling umum digunakan dalam pengukuran aliran. Orifice plate adalah suatu pelat metal yang tipis dengan lubang ditengah2nya.  Aliran dapat dilihat dari pemasangan orifice, lubang yang tajam adalah tempat upstream/aliran masuk dan lubang yang agak landai sebagai tempat downstream/tempat keluar.

Ketika orifice plate di pasang pada aliran (biasanya dipasang diantara flanges), orifice meningkatkan laju alir melalui lubang orifice yang kecil yang mengakibatkan adanya perbedaan tekanan (DP). Tekanan ini difungsikan sebagai laju alir / flow rate.

Keuntungan menggunakan Orifice Plate :

  1. Perbedaan tekanan yang tinggi dapat dihitung
  2. Memiliki data lengkap
  3. Harga dan cara pemasangan yang murah dan mudah
  4. Gampang diganti

Kerugian menggunakan Orifice Plate :

  1. Tidak dapat digunakan pada fluida yang kotor yang dapat mengakibatkan erosi pada orifice tersebut
  2. Tingginya terjadi kehilangan tekanan secara permanen

2. Venturi Tubes

Untuk pemakaian dimana tingginya kehilangan tekanan secara permanen tidak diperbolehkan, venturi tube digunakan. Dikarenakan tempat masuk dan keluar secara bertahap berkurva seperti gambar dibawah.Venturi Tube

Tetapi, Venturi tube sendiri memiliki kekurangan :

  1. Kalibrasi yang telah dihitung, kurang akurat daripada orifice plate
  2. Dibutuhkan transmiter aliran dengan sensitifitas yang tinggi, karena perbedaan tekanan yang dihasilkan lebih rendah daripada orifice plate.
  3. Lebih Besar dan lebih mahal.

3. Flow Nozzle

Flow nozzle juga disebut setengah venturi.
Flow NozzleNozzle

Flow nozzle memiliki gabungan sifat dari orifice plate dengan venturi. Karena bentuknya, flow nozzle memiliki sifat kehilangan tekanan permanen yang rendah daripada orifice plate tapi lebih tinggi daripada venturi. Flow nozzle juga lebih murah daripada venturi tube sendiri.

Flow nozzle digunakan pada pengukuran aliran dengan kecepatan alir yang tinggi. merekalebih kuat dan tahan erosi daripada orifice plate.


Instrumentasi adalah seni dalam pengukuran nilai suatu parameter pada tekanan, aliran, level, dan tempratur yang menghasilkan sinyal yang dapat dibaca atau di konversi dalam suatu parameter, cth : psig, MMscfd, %.

Sinyal output adalah standar sinyal yang dapat diproses oleh alat lain untuk pembacaan, alarms ataupun untuk kontrol otomatis. Sinyal electronic biasanya menggunakan 4 – 20mA dan sinyal pneumatic menggunakan 20 – 100 kPa.

Pressure Gauge Thermocouples Rosemount Transmitter