Redlion DSP to GE Multilin 269 Plus

[cockrell960]

Hello,

I am having an issue communicating with a GE Multilin using a Redlion DSP. My goal is to get the RTD values from the multilin and write them to a compact logix l33er using an rtd int array. This is what I have done so far. I am using a rs 485 to rs 232 B&B communications converter which I use to get online with the ge program on the computer. I have attached that to the RS232 port on the DSP. In the DSP I am using the rs232 universal Modbus master with the proper address (I assume) to the multilin. I get both red and green blinking lights on the DSP which to me means I am communicating with the Multilin but when I create a tag to verify I am receiving data I get nothing or n/a. The address I have found for rtd 1 in the 269 plus manual is 40543 but still I receive no data to the redlion. I am attaching my redlion program so far. I have no experience with Modbus so any help would be appreciated. Thank You

 

[Ken Roach]

Are you sure that the Multilin 269 Plus is set for Modbus Slave Address 2 ? The default slave address of a Multilin 269 Plus is 254, and you have to configure that value during setup.

You might also configure a delay time in the Protocol Options for PLC2. Right now it's set for "default"; try 100 or 200 milliseconds.

Also, there's a "Ping Holding Register" function in the PLC1 Protocol Options that is causing the DSPLE to read Modbus register 40001. While that should not be a big problem, you can try disabling the feature by setting that field to zero.

RS-485 is notorious for being difficult to get the polarity right; as with all RS485 devices, try swapping the data conductors.

 

[cockrell960]

I got it working thanks. The main issue was the rs232 to rs485 converter I was using. The redlion was talking to the conveyer but would not talk through the converter to the dsp. Once I took that out of the equation and made my own network cable using pin 2 as A 6 as gnd and 7 as B I started talking and getting the data. Did have to change the program since I was using rs485 port on the dsp but that was easy. Thank you