485 (GModbus) CRC/LRC error

[teslac]

    I am getting a CRC/LRC error from a half duplexed 485 system connected to a Watlow controller.  I have the instrument configured in MAX for 4-wire auto and I have this code running on other identicle systems with out an issue.  Does anyone have an idea as to what would cause such an error?

[K C · Accepted solution]

In most cases I know a 485 connection is a 2 wire connection. Maybe you should set MAX to 2-wire auto.

Kees

[teslac]

That would be good to try but unfortunatley MAX has that section greyed out and I cannot change it and am not sure how to get MAX to let me.  Do you know why MAX has that greyed out?

[K C]

I think it depends on the kind of interface you are using. Is it from NI or ?

[teslac]

 It turns out that the reason for it being greyed out was to change the advanced functions you must logon to MAX as admistrater.  Once I had access I changed the 4-wire to 2-wire auto and the system worked fine.