ModBus RTU mit größerem FrameSize

The limit for MODBUS function 03 (READ HOLDING REGISTERS) is to read 125 words with a single request. So, you have not reached the limit. However, even if you did, I do not see what stops you to read more data in multiple requests. I read more then 300 floats (that is 600 words) with multiple requests without any problem. You can have polling cycle consisting of one request for 20 words, then another for 100, then another for 70, then another for 900 bits, then another and another, and then repeat the whole cycle. It's up to you how will you organize your polling requests. I usually put critical tags in a fast polling group (for example every 1000 ms), and less critical tags in a slow polling groups (like 5000 ms for slow changing temperatures). To avoid congestion group periods can be further optimized by using prime numbers, but that is quite another topic.

Ok. If online translation was good, you mentioned 118 words at first, and then 140 words. Let's say the last is correct and your client wants to read 140 words in a single request. Page 13 of Modbus standard document says "The maximum size of a MODBUS RTU frame is 256 bytes" (RTU=SlaveAddress+FunctionCode+Data+CRC). Since 140 * 2 = 280, your client asks for something that is not possible with the standard MODBUS protocol. That means your client needs 2 requests to read 140 words. I do not see a problem with that, since that is a way zillion MODBUS masters read their data from MODBUS clients.