16.1.2 MSTR Inputs and Outputs

Figure 38 indicates the inputs and outputs associated with MSTR instructions.

INPUTS

 

 

 

OUTPUTS

 

 

 

 

 

 

Activ ate MSTR Instruction

 

MSTR Instruction

 

 

Instruction Activ e

 

 

 

 

 

40050

 

 

 

 

 

(Control Block)

 

 

Terminate MSTR Instruction

 

40100

 

 

Instruction End - Error

 

 

 

 

 

 

 

 

 

 

(Data Area)

 

 

 

 

100

 

 

Instruction End - No Error

 

 

(# data registers)

 

 

Figure 38: MSTR Inputs and Outputs

16.2 MSTR Function Error Codes

Table 8 indicates the error codes that may be output in the “4x+1” location of the MSTR control block. These specific error codes can be generated by the MBP-100. Additional error codes may be generated from other sources on the Modbus Plus network.

 

Table 8: MSTR Error Codes

 

 

Error Code (Hex)

Meaning

3001

Slave device does not support the requested function

3002

Nonexistent slave device registers requested

3003

Invalid data value requested

16.3 MSTR Read Example

The following example demonstrates how to use the MSTR instruction to read 2 registers starting at register 1 from an MBP-100 located at Modbus Plus network address 2.

1.Set up a ladder logic program as shown in Figure 37. Set the top portion of the MSTR Instruction to 40050. This will be the starting address of the MSTR Control Block. Set the control block registers to the following values:

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