Using GRV-CSERI ports from a program


#1

We are integrating a device using a RS-485 connection, and we have installed a GRV-CSERI to do this.

I have some questions:

There are some operations that we want to perform on this device when the strategy is not running.

From the shell account, I can see the that devices /dev/ttySerMod0.0 – /dev/ttySerMod0.3 have been defined.

  1. Can I write a linux program to directly write to these devices?

  2. If a strategy has been loaded, are that strategy’s I/O settings used to specify the # wires, termination, and bias settings for the device. If not, how can this be done? (I have looked at this forum post: Configure Epic Serial Module GRV-CSERI-4 but I do not see this question addressed in that post).

  3. Also, the GRV-CSERI requires that a termination mode and a bias setting by specified as part of the configuration. I have read this blog post:
    https://blog.opto22.com/optoblog/rs-485-to-terminate-bias-or-both
    that describe what termination and bias are. It is somewhat helpful. If we selected the “Termination” option, is this the equivalent of adding a 120 ohm resistor to the communication lines?


#2
  1. Great question. I don’t know. Will try and see what I can find out.

  2. If a strategy has been loaded, the module will use those config settings. If a strategy has not been loaded, then you can configure the port type via groov Manage.

  3. https://documents.opto22.com/2296_groov_Serial_Modules_Data_Sheet.pdf
    It mentions in there that the termination option is 120 ohms.