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Description
iSMA-B-4U4O-HAbout the product The module is factory equipped with the two most popular open communication protocols: ModbusASCII RTU andBACnetMSTP, which are selected using DIP switches. Addressing the modules is via rotary switches, which facilitates and accelerates the process of commissioning the system. Built in mini USB allows for initial configuration of the unit without power supply. BMS Compatibility System Controller Tridium Jace3, Jace6,
About the product
The module is factory-equipped with the two most popular open communication protocols: Modbus ASCII/RTU andBACnet MSTP, which are selected using DIP switches.
Addressing the modules is via rotary switches, which facilitates and accelerates the process of commissioning the system.
Built-in mini USB allows for initial configuration of the unit without power supply.
BMS Compatibility 
 
4x Universal Inputs (4UI)
All universal inputs have 16-bit resolution which support the following types of inputs:
- Temperature input support the following types of sensors: 10K3A1, 10K4A1, Carel 10K, 20K6A1, 2.2K3A1, 3K3A1, 30K6A1, SIE1, TAC1, SAT1, Pt1000, Ni1000 For sensor Pt1000 and Ni1000 use only 16bit resolution
- Voltage input 0-10VDC: input resistance 100kΩ accuracy ±0,1% measurement resolution 3mV@12bit and 1mV@16bit
- Current input 0-20mA - Required external resistor: 200 Ω, sold separately
- Resistive input 0-1000kΩ: measurement resolution for 20kΩ load 20Ω@12bit and 1Ω@16bit
- Dry contact input
4x Digital Outputs (4DO)
- Relay output (NO) max. 3A, 250V AC/30 VDC
Platform
- Cortex-M3
Communication
- Interface RS485 half duplex
- Up to 99 devices on the bus
- Protocols: MODBUS or BACnet
- Baud rate: 2400 to 115200 bps
Power supply
- 24V AC/DC
Housing
- Dimension: 35x110x62 mm.
- Construction: plastic, self-extinguishing (PC/ABS)
- DIN rail mounting (DIN EN 50022 norm)
- Cooling: internal air circulation
Environments
- Operating temperature: -10°C to 50°C
- Storage temperature: -40°C to 85°C
- Relative humidity: 5 to 95%, no condensation
- Ingress Protection Rating: IP40 – for indoor installation 
 Do you have a question about this product?
 
In the DOWNLOAD session you can find:
- The ISMA driver for Niagara, which contains the ISMA device Palette
- Isma configurator which is needed for updating firmware and configure modules
- Templates for Siemens sensors for Niagara (Generic Tabular) - Ni1000 Ohm at 0°C - PTC T1 (Resistance/Voltage) - Pt100 Ohm at 0°C - Pt1000 Ohm at 0°C - Pt1000 Ohm at 0°C - Pt1000 Ohm at 0°C - Pt1000 Ohm at 0°C - Pt1000 Ohm at 0°C  -    Ni100 Ohm at 0°C - Ni100 Ohm at 20°C - NTC 107 Ohm at 20°C - NTC 150 Ohm at 31°C - NTC 1 kOhm at 20°C - NTC 1 kOhm at 20°C - NTC 2 kOhm at 20°C - NTC 3850 Ohm at 0°C - NTC 500 Ohm at 20°C - NTC 575 Ohm at 20°C - NTC 8250 Ohm at 19°C
Shipping Notes
- Free Standard Shipping on $100+ Orders to the USA.
- Except Preorder products are shipped in 48 hours.
- Delivery to the USA:
- Standard Shipping : 3-10 business days
- If time is of the essence, please consider selecting expedited delivery for faster service.
Exchange/Return Notes
- We offer a 30-day return/exchange service after receiving.
- Final sale items are not eligible for returns or exchanges.
- To process your return/exchange, please contact us at [email protected]
- Please click here for more details>>> Return & Exchange Policy
4.3 ★★★★★
Based on 19 reviews
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Product Reviews
★★★★★ 3
Replacing a RXA770/780/880? You May be Disappointed.
Style: Receiver
I will start with the issues. (1.) HDMI audio drop outs. This can be fix by going into your tv and changing your audio settings from auto to pass through. However I remember this causing an inconvenience of some sort. I did not have to make this change with Marantz M1, Sony AZ1000, Or Integra DRX3.4. (2.) when unit goes into auto-standby while using the digital optical input, it will freeze after turning it on again. I had to unplug it to get it to work correctly. this happened every time. (3.) The plastic front panel can scratch easily. You may want to use a can of air to clean it. Yamaha should have flipped the design-the metal/aluminum where the glass/plastic is and the plastic where the metal is. (4) If using the coaxial for tv audio, It will take 9 full seconds before audio is heard. I had to buy a new TV(this was before the other issues were discovered). Finally (5) if you are replacing a RXA770/780/880, you may be disappointed. You'll have to step up to the RXA4A to get the features like PEQ and menus you had with them.
Sound and Power: The 2 channel specs between the Yamaha RXA2A and The Yamaha RN1000A stereo receiver are similar. Don't let that fool you. The RN1000A is way more powerful and sound much better with music, however the A2A was way better than the RN1000A for movies and tv. In full range, sub off, the RXA2A could not drive the Polk RTIa5's well with music. In fact, to me the Marantz M1class D and the Sony AZ1000 70/70w class AB sounded more powerful and musical, making them easier to listen to than the A2A. The Integra best all 3 AVR's for music in full range mode without a sub to my ears. But with the 3.4, the sub output volume was way too low, I hated the click noise(sounds like it powered on again) when turning up master volume, and I couldn't use the presets without changing the source. The Yamaha RN1000a is the best for music only, especially at a sale price.
My Positives:
It come with a 5 year warranty when registered. It's well built, especially better than the Sony. You get 8 presets that you can set to the same source or different sources almost any kind of way. The dialogue mode works very well even for music. Yamaha Support is very helpful. If yours don't come with the above issues/defects that I listed, I think it can be easy to just set it, forget about it and enjoy it.
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Reviewed in the United States on February 8, 2026
★★★★★ 5
Excellent AVR!
Style: Receiver
Our projector in our home theater died and I updated to a 4K projector. I was using a 10 year old Onkyo receiver. It was still working fine, but being that old it did not have the latest audio codecs or 4K HDMI, so I decided to go ahead and upgrade my AVR.
I had bought a relatively inexpensive Yamaha for our living room TV a few years ago and have been pleased with its performance. I looked at the RX-A2A and RX-A4A. After reading numerous reviews and tests, I decided to go with the A2A, since it was on sale and much less expensive. The difference in features were not important to me. I only need one HDMI output and only have three inputs. While the A4A has a more powerful amp and better power supply, I thought the A2A would be sufficient since our home theater is "cozy" about the same size as a living room. My speakers in my 7.1 setup are very efficient and we play music and videos at a reasonable loudness.
Still, I was concerned that the A2A would match the performance of the Onkyo with its beefier power supply and more power. My fears were soon put to rest.
After swapping out the units, I set up the A2A. It only took 10 minutes, including running YPAO to calibrate the system. I designed the room carefully and it has acoustic treatments, including bass traps. Therefore, the adjustments made by YPAO were minimal. We watched "No Time to Die", which has a well-regarded soundtrack full of dialog, music and special effects, including some beefy LFE. The A2A handled it all with aplomb, even at a higher-than-normal volume setting. I felt there was a noticeable improvement in audio quality. My adult son, who didn't know I upgraded to the Yamaha, remarked how the audio sounded more balanced and refined, which he attributed my sound treatments (he'd already heard the Onkyo after I had installed them).
Video quality is also excellent, seamlessly passing the HDR 4K signal to the projector. Although I'm frugal and didn't want to upgrade my AVR, I'm glad I did. I'm also glad I went with the A2A.
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Reviewed in the United States on July 8, 2024
★★★★★ 5
Yamaha RX A2A
Style: Receiver, Style: Receiver
It was time to replace my old receiver with a current version. Much of the technology has changed when comparing receivers today versus 20 years ago. However, the Yamaha RX – A2 A offered a great balance between price and features. Hooking up my existing components and high definition television was extremely easy. I would recommend downloading the users manual from the Yamaha website to brush up on all options and features available during set up. The sound reproduction is top notch. I also hear the difference in surround sound reproduction compared to my older model. Once you spend quality time setting up your receiver to reflect the setup you desire, this model does not disappoint. I was able to set up my second zone so I can listen to a completely different input compared to the main room. I especially like the value added Bluetooth feature so I can connect directly to the receiver without any wires connection.
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Reviewed in the United States on March 11, 2026
★★★★★ 5
Great Yamaha quality and features as expected.
Style: Receiver
Love it! Easy set up lots of options. Beautiful immersion sound.
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Reviewed in the United States on August 27, 2025
★★★★★ 5
Exceeded expectations
Style: Receiver
We have 2 tower speakers, 4 ceiling speakers, a center speaker, and two subwoofers and, wow, the sound is amazing. The key is the microphone which is used to set the relative volume and delay time for each speaker. Comes with media app which allows access to my audio files on my network storage device and lots of streaming apps. Kudos to Yamaha.
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Reviewed in the United States on February 1, 2026