Experimental Physics and
Industrial Control System

Hi folks! 

 

This question is probably specific to Gary, but I’m sending it to the list, because the information will hopefully be helpful to the next person who tries this. 

Also, apologies for the lengthy email, but I’m trying to make sure all the information is included. 

 

I’m trying to understand how the modbus read functions are designed.  I see following line in your st.cmd [1]:

drvModbusAsynConfigure("watlow_AI_Num_1.1", "watlow1", 0, 4, 360, 62, 7, 2000, "watlow1");

which is reading 62 bytes starting at modbus address 360, and assume that they are type INT32_BE

2 lines later it says:

drvModbusAsynConfigure("watlow_AI_Enum_1.1", "watlow1", 0, 4, 362, 82, 6, 2000, "watlow1");

Which says read 82 bytes starting at address 362, and assume that they are type INT32_LE_BS [2]

 

I mapped the information from the manual, and put it in a file at:

https://github.com/gregoryleblanc/CsHeater/blob/main/AnalogInput.md

 

I’m guessing that the num line is reading in floats, and the enum line is reading in the same data, but reading the uint values, and there is something wonky about the byte order that you can’t read them into the same space. 

 

Based on what I’ve gleaned, I’ve pared things down to a small config.  I’m not seeing any errors when I run st.cmd, and inside my ioc I see:

epics> dbl

:SE:Watlow:1:ControlModeActive1

:SE:Watlow:1:AutotuneStatus1

:SE:Watlow:1:ControlModeActive2

:SE:Watlow:1:AutotuneStatus2

:SE:Watlow:1:HeatPower1

:SE:Watlow:1:CoolPower1

:SE:Watlow:1:ProcessValue1

:SE:Watlow:1:ActiveSV1

:SE:Watlow:1:HeatPower2

:SE:Watlow:1:CoolPower2

:SE:Watlow:1:ProcessValue2

:SE:Watlow:1:ActiveSV2

 

Next, I tried grabbing ProcessValue 1 and 2:

$ caget :SE:Watlow:1:ProcessValue1 :SE:Watlow:1:ProcessValue2

:SE:Watlow:1:ProcessValue1     3.59505e-06

:SE:Watlow:1:ProcessValue2     0

 

Which doesn’t seem to match up at all with what I see on the controller:

https://www.flickr.com/gp/gregoryleblanc/gD9270

https://www.flickr.com/gp/gregoryleblanc/2TRm59

 

I’m not sure where to go from here. 

     Greg

 

P.S. I’m hoping to map out the other data read blocks later in the week.

P.P.S. I have a patch to replace the numerical datatypes in your st.cmd with more descriptive strings.  Should I submit a pull request?

 

1: https://github.com/tauferg/Watlow-PM/blob/ea5096bf72f29eb42e3f2c2f5ee1a12ceb089863/Watlow_PM862FJ-3LEJAA_IOC/st.cmd.ModbusAddresses%20Only#L27

2: Little-endian byte swapped?  Somehow there’s got to be a tie between PDPs and Modbus, and I’m a bit scared.

--

Gregory Leblanc

Accelerator Engineer

Edwards Accelerator Lab - Ohio University

123 University Terrace

Athens, OH 45701

leblanc at ohio.edu

M: (401) 52-OUAL1 or (401) 526-8251