RKC PZ900 temperature controller

[arienai]

Hello, 

I will receive soon a PZ900 from RKC Japan. It is a temperature controller similar to Eurotherm models. 

I downloaded the manuals, drivers, softwares. But the drivers are not for Labview, but for RS422 communication from a software and the PZ900. 

I would like to develop my own labview driver for controlling this instrument, and basically, I just need SET T and READ T commands. That's all I need. 

Can someone explain me what should I learn to make this driver ?

I will appreciate any advices. I already search, get manuals, etc... I do not request to get a driver already made, I just want to learn the good way to tackle this new problem.  

(I have Labview Core 2, I developed a labview program that is already controlling 12 instruments, but this PZ900 is totally different than DMM, lock-in, SMU, etc... so I need to go one more step beyond with labview learning, specifically to this type of instrument PZ900. I guess it is a question of MODBUS or something like this. I am not familiar with that, I probably need a few example to understand what kind of work I should do with the PZ900 to create my driver)

[GerdW]

Hi arienai,

---

@arienai wrote:

I downloaded the manuals, drivers, softwares. But the drivers are not for Labview, but for RS422 communication from a software and the PZ900. 

I would like to develop my own labview driver for controlling this instrument, and basically, I just need SET T and READ T commands. That's all I need. 

(I have Labview Core 2, I developed a labview program that is already controlling 12 instruments, but this PZ900 is totally different than DMM, lock-in, SMU, etc... so I need to go one more step beyond with labview learning, specifically to this type of instrument PZ900. I guess it is a question of MODBUS or something like this. I am not familiar with that, I probably need a few example to understand what kind of work I should do with the PZ900 to create my driver)

---

Unfortunately you forgot to attach the manual to your message…

In which way is this PZ900 "totally different" to a DMM? For both devices you send a command and then you receive an answer/response!

So you need to open a communication using VISA, send commands and receive the answers. Upon exiting your program you close the VISA reference. You can use any "DMM"-type device driver for inspiration, like those for Keithley2000 devices…

(How does MODBUS come into play?)

[arienai]

Dear GerdW,

here are the links : 

https://www.rkcinst.co.jp/english/downlaods/8918/imr03b07e1/

https://www.rkcinst.co.jp/english/wp-content/uploads/sites/2/2019/06/imr03b05e1.pdf

This instrument will not be on localhost with TCP. It will be plugged to the computer by USB connection. (through the maker module COM-K1 , to convert RS422 to USB).

Today, I downloaded and installed Modbus library on my Labview 2019 (Win 10, 64 bit). I found an example based on TCP. I need to convert this example to SERIAL. 

In the manual, section 6.4 of the document imr03b06e1.pdf, it deals with single word data. I found item 1 related to "measured value (PV)", related to "Register address 0", and also "Set Value (SV) monitor", related to "Register address 1". 

Looks quite simple. I will try during this week. The machine is arriving tomorrow. 

Yours

[GerdW]

Hi arienai,

---

@arienai wrote:

This instrument will not be on localhost with TCP. It will be plugged to the computer by USB connection. (through the maker module COM-K1 , to convert RS422 to USB).

Today, I downloaded and installed Modbus library on my Labview 2019 (Win 10, 64 bit). I found an example based on TCP. I need to convert this example to SERIAL. 

In the manual, section 6.4 of the document imr03b06e1.pdf, it deals with single word data. I found item 1 related to "measured value (PV)", related to "Register address 0", and also "Set Value (SV) monitor", related to "Register address 1". 

---

Which Modbus library did you download and install? Most often they provide examples for serial communication (Modbus/RTU) as well…

Did you configure your device to use Modbus communication as described in the manual?

You did not provide a link to "imr03b06e1" so I can't tell about setting SV or reading PV data…

[arienai]

Sorry, I though it could be reached through the links I mentioned. 

I attached those documents in a ZIP file. 

So far this is what I have, but I am not so familiar with the content ... 

I will see when the PZ900 will arrive in the lab tomorrow . 

I will connect it to a desktop through USB. 

Once again, thank you for taking time to help me, or simply to read those docs, cause the content is a little bit complicated. But maybe it is not that difficult by using modbus toolbox. 

[arienai]

I received COM-K2 module to plug the PZ900 (Modulus/RTU) to a PC via USB cable. 

The PZ900 can be controller by an available software PRO-TEM from RKC. To use it, I have installed the drivers of the com module COM-K2, then run PRO-TEM, and I could send commands to set temperature, and read temperature. However, I have no idea about the structure of the instruction. 

The attached programming guide, is helpful to understand. 

The PZ900 is detected as COM10 on device manager (Win10 - 64bit). 

However, I could not send command with VISA like I used to do for DMM or other instruments that are "Labview compatible" (with LV  drivers ). 

So I guess I have to send hexadecimal instructions to be able to communicate with this PZ900. 

I will try to do it. But if you have a small example of labview vi that could do that, I will be very grateful. 

[GerdW]

Hi arienai,

your manual describes the "PLC communication". You should read the "host communication" manual instead, as mentioned on page 1-2. (It mentions "Modbus"…)

[arienai]

Thank you GerdW, I attached the host com manual.

I have to read it, but if I understand the principle of creating 1 instruction, then I can (maybe?) do similarly for all commands and create a driver for PZ900.

A short example of write/read/query will be more than appreciated. I hope I will be able to send 1 command to PZ900 using this Modbus protocol. 

Example 1 : set temperature  239.5 (degree C), infinite time duration

Example 2: ramp temperature from initial Ti to final Tf in 10min

Example 3 : read temperature like 573.2 (deg C) after conversion from hexadecimal to decimal and the decimal point is not recognized... 

This is almost what I need for the moment. Next, I will have to define PID ... which is maybe more complicated. 

Yours

[GerdW]

Hi arienai,

your device supports two different type of protocols: the "RKC" one and a standard Modbus protocol.

You may implement the RKC-type protocol as described in chapter 4, but I suggest to use Modbus with one of the available libraries. All you need to learn is to use the correct Modbus registers and the correct data encoding - as described in chapter 5 & 6…

[arienai]

Dear GerdW

MODBUS order of data transfer is set from "high-order word to low-order word". 

Actually, the settings are for input data type = DOUBLE WORD. 

The number of measured value digits is 5. 

(The com data type can be checked in Modbus double word by : 013EH, 013FH )

Could you just tell me the difference between programming with "high-order to low order" and "low order to high order" ? 

What is the difference between programming in "double word" and "single word" ? 

The master is the PC. 

The slave address (PZ900) is 01

The parameter ADD (device address) has been set to 1 in order the master to communicate with the slave. 

I noticed the slave address is 1, but it is 2bits, so it should become 01. 

In MODBUS, the message format is : 

slave address : 01

function code : 03H (to get temperature )

data

error check (CRC-16) 

Based on page 6-3-1, double word, could you confirm that the correct sequence of instruction should be  : 

- measure value (PV) : 01 03H 00H 00H 00H 04H 44H 3AH  --> is it correct ? 

- set value (SV) monitor : ?? 

Actually, I am interested in FIX set mode control : set temperature T. 

But also by a RAMP in temperature until Temp T, followed by a plateau at T with infinite duration (until setting another temperature). 

The reason of the RAMP is that I can control the amount of power to prevent damages on the hot plate (hardware)

As mentioned in 5-13, there is a warning for the decimal numbers, as MODBUS does not recognize data with decimal point.

Then, I cannot understand how PZ900 can understand a set value 298.5 for example. There is 5 digits and 4 bytes data, so it is OK, but how PZ900 can interpret the decimal part ? 

So here is back to orignal question about the difference between programming in single word rather than double word : is single word prevent decimal settings ? 

Further, ...  the MODBUS data mapping will break my brain ... for sure !