Issue with multiple pzems - solved about pzem-004t-v30 HOT 5 CLOSED

I've read the Adafruit Discord channel thread about this issue... I wasn't conscious at all of the memory problem (which isn't strange as I'm a complete beginner to C++...). Although I'm not planning to use as many sensors, I'd also do it like this on my sketch. Thanks to @mzero!

Now, you could try to combine this approach with the array's one (at the end of this post), I read @mzero said it didn't solve the memory issue by itself, but combined with your mod it'll probably work.

The code could be like this (using the modified library, of course):

####################################
SoftwareSerial serial56(D5, D6);
SoftwareSerial serial34(D3, D4);
SoftwareSerial serial12(D1, D2);

PZEM004Tv30 pzem[18] = {
  PZEM004Tv30(serial56, 0x01),
  PZEM004Tv30(serial56, 0x02),
  PZEM004Tv30(serial34, 0x03),
  PZEM004Tv30(serial34, 0x04),
  PZEM004Tv30(serial12, 0x05),
  PZEM004Tv30(serial12, 0x06),
  PZEM004Tv30(serial56, 0x07),
  PZEM004Tv30(serial56, 0x08),
  PZEM004Tv30(serial34, 0x09),
  PZEM004Tv30(serial34, 0x0a),
  PZEM004Tv30(serial12, 0x0b),
  PZEM004Tv30(serial12, 0x0c),
  PZEM004Tv30(serial56, 0x0d),
  PZEM004Tv30(serial56, 0x0e),
  PZEM004Tv30(serial34, 0x0f),
  PZEM004Tv30(serial34, 0x10),
  PZEM004Tv30(serial12, 0x11),
  PZEM004Tv30(serial12, 0x12)
};
####################################

The memory problem is avoided as only 3 instances of the soft serial port are created, instead of 18.

And when you read the sensors, instead of using (example for sensor nº5):

float voltage = pzem5.voltage();

You should use:

float voltage = pzem[4].voltage();

With the great advantage that you can use a variable instead of the fixed number, so you can include that into a loop, for example.
(Note I'm using 4 instead of 5 in the second case because the array starts at 0, so the pzem's are numbered 0...17 instead of 1...18).

It would be very good if mandulaj included this simple mod in the main branch. Apparently, is fully backward compatible with the present version and best suited for multiple sensors (a use that, probably, was unforeseen when designing the library, as @mzero said).

from pzem-004t-v30.

Another question: You don't really need to use different serial ports for each 6 PZEM's if you use a buffer between microcontroller's TX and PZEM's RX. This can be as simple as a single PNP transistor. This way, you can free 2 GPIOs for other uses (and save two soft serial port instances). Also, it's better to connect the PZEMs to +5V instead of 3.3V to avoid saturating the WemosD1 weak regulator.

In the previous posts to that one, you can also see considerations about the current used by each PZEM and also a mod I made to the library that allows passing the address of the PZEM as a parameter (I'll try to combine it with the one proposed here).

from pzem-004t-v30.

1. @morganflint thats a good point with the array & loops, i already tried but i wasnt able to manage to work the correct syntax for client publish. There the topic must be inside quotes and dont know how to make it variable

example:

for (int i=0; i<18; i++){
Serial.print("pzem "); Serial.println(i+1);
float voltage = pzem[i].voltage(); client.publish("/topic/pzem[i]",String(voltage).c_str());
}

this is the issue:"/topic/pzem[i]" in mqtt explorer i can see it created new topic /topic/pzem[i] instead of pzem1..pzem18... any idea ? thanx

2. i am powering via 5V, 3.3v didnt work good.
3. i have no use for additional gpio so adding pnp transistor might be good idea but not for my setup and will it leave this way

from pzem-004t-v30.

I haven't worked with mqtt so I'm not sure if this will help but I'm afraid client.publish("/topic/pzem[i]",String(voltage).c_str()) is not working because the variable i is inside the quotation marks, so it's considering it part of the string and not as a variable.

I'd try to define an array also for mqtt topics, something like:

String topic[18] = {
"/topic/pzem1",
"/topic/pzem2",
...
"/topic/pzem18"
};

And then:

float voltage = pzem[i].voltage(); client.publish(topic[i],String(voltage).c_str());

Maybe you can get better ideas from here.

from pzem-004t-v30.

It looks like, this issue was resolved. I am closing it now.

from pzem-004t-v30.