Instructions For The Modem Module - Siemens SIMATIC S7-200 System Manual

Instructions for the Modem Module

MODx_CTRL Instruction
The MODx_CTRL (Control) instruction is used to enable
and initialize the Modem module. This instruction should be
called every scan and should only be used once in the
project.
MODx_XFR Instruction
The MODx_XFR (Data Transfer) instruction is used to
command the Modem module to read and write data to
another S7-200 CPU or a Modbus device. This instruction
requires 20 to 30 seconds from the time the START input is
triggered until the Done bit is set.
The EN bit must be on to enable a command to the module,
and should remain on until the Done bit is set, signaling
completion of the process. An XFR command is sent to the
Modem module on each scan when START input is on and
the module is not currently busy. The START input can be
pulsed on through an edge detection element, which only
allows one command to be sent.
Phone is the number of one of the data transfer telephone
numbers. You can use the symbolic name you assigned to
each data transfer telephone number when the number was
defined with the Modem Expansion wizard.
Data is the number of one of the defined data transfers. You
can use the symbolic name you assigned to the data
transfer when the request was defined using the Modem
Expansion wizard.
Done is a bit that comes on when the Modem module completes the data transfer.
Error is a byte that contains the result of the data transfer. Table 10-4 defines the possible error
conditions that could result from executing this instruction.
Table 10-6 Parameters for the MODx_XFR Instruction
Inputs/Outputs
START
Phone, Data
Done
Error
Creating a Program for the Modem Module
Data Type Operands
BOOL I, Q, M, S, SM, T, C, V, L, Power Flow
BYTE VB, IB, QB, MB, SB, SMB, LB, AC, Constant, *VD, *AC, *LD
BOOL I, Q, M, S, SM, T, C, V, L
BYTE VB, IB, QB, MB, SB, SMB, LB, AC, *VD, *AC, *LD
Chapter 10
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