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Recommended Low-Cost Modbus RTU Mixed-Signal Remote I/O Module
Seeking recommendations for a simple, low-cost Modbus remote I/O module w/ analog I/O, digital I/O, 2A+ relays
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Howdy folks! My company is looking for a simple, low cost Modbus RTU remote IO module with digital in/out (1 ea), analog in/out (1 ea), and relay outputs (1-2), and I was hoping some of y'all would have recommendations. Simpler is better, i.e. we prefer jumper configuration over software configuration, and we're hoping to keep it under $200. Isolation is a plus, but not an absolute requirement, as is surge and ESD protection. Basically we need something that can live reliably in the field for 5-10 years. So far I've found:

http://www.datanab.com/controllers/datanab_mbus_io14_din.php

http://www.alibaba.com/product-detail/Industrial-Modbus-I-O-Module-RTU_60265056638.html?spm=a2700.7724838.30.1.YKmOXW

Any experience with either of these, or other recommendations? Is the Alibaba route an ok choice? Thanks!

The Alibaba link required registration, so I passed.

The Datanab I/O module looks very well designed for high level analog signals (no T/C or RTD temp sensors). I doubt the inputs are isolated at that price point; if they were, the spec sheet would brag about it.

The spec is silent on the exact thermistor it expects, and whether the input is scaled linear or raw.

I am particularly impressed by the on/off enabling of RS-485 bias and the simultaneously Modbus master/slave functionality with dual 485 ports.

I'm not familiar with the MBus_ioFlash software and what its use entails or what it costs. But it sounds like the free software will configure the module and the $500 pro version is for some advanced features.

Overall, looks quite functional for its $140 price tag.

Might se if they are willing to offer a loaner for testing? They are USA located.
http://www.datanab.com/contact.php

> Howdy folks! My company is looking for a simple, low cost
> Modbus RTU remote IO module with digital in/out (1 ea),

Many years ago I used a line from Moore Industries to communicate with a Modicon PLC. I think it was called a data concentrator.
They make modules for all the usual inputs, 4-20, RTD, thermocouple etc.

Hi beck92,

I use the Moxa E12xx series with Modbus TCP
http://www.moxa.com/product/Ethernet_IO.htm

Cheap, easy to use, accepts different voltages (from memory), web based setup, extremely fast I/O reads & writes (5-10ms approx).
Only complaint is the terminals are designed for small wire diameters (0.5mm2) - but I can live with this.

Cheers,
PB

Hi Beck,

We have a module which can meet most of your requirements. The main difference is that you asked for relay outputs where ours our open collector. This can be remedied if you use SSRs if you truly need higher current or voltage for your output.

http://www.icpdas-usa.com/m_7026.html

I'm using the datanab gear. Works well.