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STBAVO1250 Byte Reversal in a Profibus Island Fixed in Exec v2.02

Goals and Symptoms

If a Profibus master and STBNDP2212 island were power cycled simultaneously, when communication resumed, the output channel upper and lower bytes sent to an STBAVO1250 would occasionally be swapped. After the described power cycle was done, 3200 Hex sent to the Profibus island could result in 0032 Hex being written to an AVO output channel register. Another power cycle cleared the error and resulted in the bytes being written correctly.

Facts and Changes

No other output modules appeared to be affected. Powering the units separately did not appear to cause the problem to occur.

Causes and Fixes

The issue has been addressed with new executive software for the STBNDP2212. Those NIMs loaded with v2.02 executive software will not display the problem.
Production modules loaded with the exec are marked SV: 02.02 and PV:08.

The web accessed exec file name is ai_nim_ndp_02_02.bin.

The problem had been observed when a Siemens S7315-2DP w/2.00 firmware was used for the head. Other head configurations had not been observed to cause the problem. However, due to the intermittent nature of the problem, users were cautioned to not power cycle Profibus heads and associated STB islands at the same time.

This resolution replaces an earlier version that described the problem and indicated a fix was being investigated.

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