R4IOJ32 FAQ

Dear Sir or Madam,

We are a systems integrator , evaluating the R4IOJ32 32-channel RS-485 Modbus RTU I/O board for a parcel locker retrofit project in Western Europe.

Your product listing states "3.3 V / 5 V TTL level input", which suggests a non-isolated CMOS or TTL input stage. If that is correct, it is the reason we are contacting you — most comparable boards use opto-isolated inputs which cannot work with our signal.

Please could you confirm the following:

1) DIGITAL INPUTS — the decisive question.
The sensors we read are weak voltage sources:
- open circuit 4.7 V, source impedance approximately 1.2 kOhm
- maximum available current 3.8 mA
- logic states 0 V and 4.7 V
Please confirm:
a) the input high threshold (VIH) and low threshold (VIL) in volts,
b) the input impedance in ohms,
c) whether the inputs are opto-isolated or direct CMOS/TTL,
d) the absolute maximum input voltage — we would apply 4.7 V to a board you describe as 3.3 V / 5 V logic, and need to know this is within specification.

2) OUTPUTS.
We switch a lock control line by pulling it to ground for 500 ms. The line sits at 4.7 V open circuit through about 1.2 kOhm, so the output needs to sink roughly 3.8 mA. Can the TTL outputs do this directly, and what is the guaranteed sink current per channel?

3) QUIESCENT POWER.
What is the board's idle current in mA at 12 V? Is there a sleep or low-power mode? This is a solar-powered installation, so idle consumption is our binding constraint — we need 100 mW or less per board.

4) ENVIRONMENT.
- operating temperature range (we need at least -10 to +60 °C)
- is conformal coating available, or can the board be supplied coated?

5) CERTIFICATION AND SUPPORT.
- Do you hold a CE certificate for this board? We would need the certificate document and the issuing test laboratory, not only a declaration of conformity.
- For how many years can you commit to supplying this board? We need to be able to reorder for more than five years.
- If a security or functional issue is found in the firmware, what is your process for issuing an update?
- Please also confirm the registered company name and address that would appear on an invoice.

6) COMMERCIAL.
- unit price at 1 / 100 / 1,000 / 4,000 / 5,000 pieces
- lead time for the sample and for the volume order
- can you ship one sample unit to the Czech Republic now, and at what cost?
- do you have a distributor or representative in the European Union?

Please answer question 1 first if that is easier — if the input threshold does not match our signal levels, the rest is not needed.

Thank you and best regards,

Eletechsup :
1) DIGITAL INPUTS — the decisive question.
The sensors we read are weak voltage sources:
- open circuit 4.7 V, source impedance approximately 1.2 kOhm
- maximum available current 3.8 mA
- logic states 0 V and 4.7 V
Please confirm:
a) the input high threshold (VIH) and low threshold (VIL) in volts,
A1：VIH 6.0V, VIL 2.0V
b) the input impedance in ohms,
A2 ： > 1MΩ
c) whether the inputs are opto-isolated or direct CMOS/TTL,
A3：direct CMOS/TTL
d) the absolute maximum input voltage — we would apply 4.7 V to a board you describe as 3.3 V / 5 V logic, and need to know this is within specification.
A4 :Yes! this is within specification

2) OUTPUTS.
We switch a lock control line by pulling it to ground for 500 ms. The line sits at 4.7 V open circuit through about 1.2 kOhm, so the output needs to sink roughly 3.8 mA. Can the TTL outputs do this directly, and what is the guaranteed sink current per channel?

A:
Maximum sink current of a single I/O port (output low, current flowing into the chip): 50mA**
Maximum source current of a single I/O port (output high, current flowing out of the chip): 20mA**
Total sink current / total source current of all I/O ports: ≤120mA**

3) QUIESCENT POWER.
What is the board's idle current in mA at 12 V? Is there a sleep or low-power mode? This is a solar-powered installation, so idle consumption is our binding constraint — we need 100 mW or less per board.

A: The quiescent operating current is approximately 10mA.

4) ENVIRONMENT.
- operating temperature range (we need at least -10 to +60 °C)
- is conformal coating available, or can the board be supplied coated?

A:
1. Operating temperature (industrial grade): -40℃ ~ +105℃**AMEC Semiconductor
2. No environmental coating is provided; an environmental coating can be provided for a small fee when purchasing in bulk.

5) CERTIFICATION AND SUPPORT.
- Do you hold a CE certificate for this board? We would need the certificate document and the issuing test laboratory, not only a declaration of conformity.
- For how many years can you commit to supplying this board? We need to be able to reorder for more than five years.
- If a security or functional issue is found in the firmware, what is your process for issuing an update?
- Please also confirm the registered company name and address that would appear on an invoice.

A:
1. You can apply for CE certification yourself, or we can provide the necessary documents. Alternatively, you can pay us to handle the certification.
2. This product has a long-term supply period of over 10 years.

6) COMMERCIAL.
- unit price at 1 / 100 / 1,000 / 4,000 / 5,000 pieces
- lead time for the sample and for the volume order
- can you ship one sample unit to the Czech Republic now, and at what cost?
- do you have a distributor or representative in the European Union?

A: We recommend purchasing 5-10 samples for small-batch testing first. If the samples meet your needs, then we can discuss bulk pricing.

Unfortunately your answer rules the R4IOJ32 out for our application, and I want to explain
why, in case it is useful to you.

You state VIH = 6.0 V. Our sensor signal is a voltage source of only 4.7 V at open circuit.
It therefore cannot reach 6.0 V under any condition — not even with zero source impedance.
The board would never see a logic high from our sensors.

Two remarks that may be worth passing to your engineering team:

1) Your input impedance of over 1 Mohm is excellent for us — it means our weak 4.7 V source
would only have to deliver about 5 microamps. The current side of the problem is
completely solved by your design. It is only the 6.0 V threshold that blocks it.

2) Your product listing describes the inputs as "3.3 V / 5 V TTL level input". We read that
as implying a threshold of roughly 2 V, which is why we approached you. A VIH of 6.0 V
is quite different from what that description suggests — you may want to state the actual
VIH on the product page, as it will matter to other customers working with 5 V logic.

One last question before we close this out:

Do you have any variant, or a jumper/resistor option on the board, that lowers the input
threshold to around 2 V — or an input version without the internal divider? If such a
version exists, we would be glad to reopen the discussion, because everything else about
the board fits our needs well: the channel count, the RS-485 Modbus interface, the
non-isolated CMOS inputs, the output sink current and the price.

If not, thank you again for your time and for the straight answer.

Eletechsup
"VIH 6.0V, VIL 2.0V" means that it can recognize any voltage level between 2-6V. A voltage level of 3.3-5V is recommended.