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5.2.1. Profibus-DP Master Control Word
The output word located at addresses 16#0200 (MSB) and 16#0201 (LSB) in the gateway’s output memory
constitutes the Profibus-DP master command word. Its structure is described below:
Bits Description
15 FB_HS_CONFIRM: Acknowledgement bit of a gateway diagnostic
The Profibus-DP master must compare the value of the FB_HS_CONFIRM bit to the value of the
ABC_HS_SEND bit (bit 15 in the gateway’s status word). If these two values are different, this means
that the gateway has transmitted a new diagnostic to the Profibus-DP master.
To tell the gateway that it has read a diagnostic, the Profibus-DP master must copy the value of the
ABC_HS_SEND bit to the FB_HS_CONFIRM bit. This allows the gateway to issue a new diagnostic.
Summary:
• If ( FB_HS_CONFIRM = ABC_HS_SEND ) Æ The gateway’s status word contains a diagnostic
which has already been acknowledged by the Profibus-DP master. So the gateway is free to use
this status word to place another diagnostic there.
• Else Æ A new diagnostic is available in the gateway’s status word. The Profibus-DP master can
read this diagnostic, but must also copy the value of ABC_HS_SEND to FB_HS_CONFIRM in
order to allow the gateway to generate new diagnostics.