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Address Value
40200 Value to write to register 1 @ network address 32
40201 Value to write to register 2 @ network address 32
40202 Value to write to register 3 @ network address 32
40203 Value to write to register 4 @ network address 32
4. In this case, we are accessing four registers, so set the bottom portion of
the MSTR instruction (“number of registers”) to 4. In the case of MSTR
writes, this number cannot be greater than 100 by definition.
5. Initiate the write command by closing internal relay 1. The data at registers
40200, 40201, 40202, and 40203 will be written to registers 1, 2, 3 and 4,
respectively, of the MBP-100 located at network address 32.
16.5 MSTR Global Read Example
The following example demonstrates how to use the MSTR instruction to read
32 words of global data from an MBP-100 located at Modbus Plus network
address 10.
1. Set up a ladder logic program as shown in Figure 37.
2. Set the top portion of the MSTR Instruction to 40070. This will be the
starting address of the MSTR Control Block. Set the control block registers
to the following values:
Address Description Register Value
40070 MSTR function (global read) 6
40071 Error code Read Only
40072 Number of consecutive registers to read 32
40073 Number of words available to read Read Only
40074 Destination node address 10
40075 Master node address 1
3. Set the middle portion of the MSTR instruction to 40300. This will be the
starting address of the MSTR data area. This is the location that will
contain the data returned from the MSTR global data read transaction.
Address Value
40300 Value at offset 0 in global data from network address 10
40301 Value at offset 1 in global data from network address 10
: :
40300+n Value at offset n in global data from network address 10
: :
40331 Value at offset 31 in global data from network address 10