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Goals and Symptoms
How to restore the RS-485 communications on a 'Tesys U' connected to a Tesysport.
Facts and Changes
Causes and Fixes
If '140NOE77111 'communications to the Tesysport is recovered after a lockup, the RS-485 connection to
the 'Tesys U' does not get restored. When this happens, the ERR led on the 'Tesys U' will be flashing.
In order to re-establish the RS-485 Modbus communications to the 'Tesys U', the recovery bit (bit 3 of
word 703) must be reset.
The following is from page 58 of the 'TeSys® U LULC032-033 Modbus Communication Module
Recovery After Loss of Communication
After acknowledgment by setting bit 703.3 to 1, recovery occurs according to the states of control
bits 704.0 and 704.1.
To resolve the issue the application needs to be modified to