Delta RMC151 - Manual (Page 527)

6 Communication
registers in the Response Block to return the value of a read from any single register in
the RMC70.
When a read is requested from any single register in the RMC70, the response from this
single-register read will be placed in the Axis 0 Read Response register. In order to see
the response from the PROFIBUS, you must map the Axis 0 Read Register into one of the
Indirect Data Map registers.
Notice that the copy from the requested register into the Axis 0 Read Response register
only occurs once, and therefore you will not see the value continuously updating like the
other Response Block registers.
To read any single register from the RMC70, use the following steps:
• Wait until the Read/Write Request bit is equal to the Read/Write Acknowledge
bit. If they are not equal, the RMC70 is currently processing a read or write request.
• Clear the Read/Write bit.
• Set the Read/Write Address File and Read/Write Address Element. For example, for
address %MD8.12, the file is 8, and the element is 12. See the RMC70 Register Map
topic for a description of all RMC70 registers and their addresses.
• Toggle the Read/Write Request bit.
• Wait until the Read Request bit is equal to the Read/Write Acknowledge
bit. When they are equal, the RMC70 will have updated the Axis 0 Read Response
register with the requested data, and the corresponding Response Block register.
To further clarify the ordering, keep these basic rules in mind:
• Do change the read address and Read/Write bit before toggling the Read/Write
Request bit.
• Do not change the Read/Write Request bit after a read request until you have
processed the data in the Read Response register.
• Do not change the read address or Read/Write bit when the Read/Write Request
bit does not match the Read/Write Acknowledge bit.
Write to the RMC70
To write to the RMC70, use the following steps:
• Wait until the Read/Write Request bit is equal to the Read/Write Acknowledge
bit. If they are not equal, the RMC70 is currently processing a read or write request.
• Copy the value you wish to write to the RMC70 into the Write Value register (7) of the
Command Block.
• Enter the Read/Write Address file and element. For example, for address %MD56.0,
the file is 56, and the element is 0. See the RMC70 Register Map topic for a description
of all RMC70 registers and their addresses.
• Set the Read/Write bit.
• Toggle the Read/Write Request bit.
• Wait until the Read/Write Request bit is equal to the Read/Write Acknowledge
bit. When they are equal, the RMC70 has received the data written to it.
To further clarify the ordering, keep these basic rules in mind:
• Do change the Read/Write bit, write address, and write value before toggling the
Read/Write Request bit.
• Do not change the Read/Write bit, write address, or write value when the
Read/Write Request bit does not match the Read/Write Acknowledge bit.
Note:
The RMC70 sets the Read/Write Acknowledge bit equal to the Read/Write Request to
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