READ_VAR 16#0100 error

[alekseib]

I have BMXNOM0200 module with 2 RS-485/232 ports. Each port has its own devices connected. For some reason, both READ_VAR blocks began to produce error #0100 (256). Other READ_VAR blocks on other BMXNOM0200 modules work fine. When I remove BMXNOM0200 module from the backplane and insert it back it starts to work, but after some time everything repeats. As I understand from the help, this error means "No resources towards the processor". This looks strange because we have BMEH584040 controllers that are not loaded at all. What could be the problem?

[Marian_Pavlik]

error #0100 = Request not processed

error #01FF = No resources towards the processor

There is one shared data buffer for both channels in BMXNOM0200. As result is that problems at one link could lead to buffer overflow and activity bit = TRUE for long time.

There is need to check Activity bit at zero before execute READ_VAR function again.

[ProfHameedi]

Hi.

in order to avoid any hanging or unexpected behavior of using READ_VAR or WRITE_VAR function block, you need to:

1- Assure number of READ_VAR blocks executed in a single PLC scan to be less than 8.

2- Assure that establishing communication of multiple serial devices on the same physical port is managed (no simultaneous requests on the same port).

3- Assure that the time gap between 2 consecutive requests on the same port is sufficient to send request and receive the response.  

[Aswin_Raj]

Hope this might help.