DLG LMP-100, User Manual

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LMP-100
PROFIBUS/MODBUS GATEWAY
Page 28 of 40 LMP-100 User Manual MAN-EN-DE-LMP100-01.00_14
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Control register
The LMP-100 provides the user with a data area called control register, where several
settings can be performed on the device.
The control register is located at the start of the Profibus output buffer, occupying the first
16 bytes. Therefore, to calculate the location of data consumed by the write rules it must be
considered that data is arranged immediately after the control register, after byte 16.
The control register contents are shown below.
byte 0 byte 1 bytes 2 – 6 bytes 7 – 15
Slave address Slave activation control Write triggers Reserved
Bytes 0 and 1 of the control register allow controlling the activation of Modbus slaves.
Activation means the possibility of stopping and reestablishing communications with a Modbus
slave while the LMP-100 is operating, without the need for Modbus rule reconfiguration.
As explained before in the rule configuration section, each rule has a parameter called
“Enabled”, with the purpose of avoiding that a the rule produces activity in the Modbus network.
This parameter is interesting in situations such as failure or removal of a Modbus slave, which
cause network timeouts due to rules that address the referred slave. The “Enabled” parameter
can be set to value “No” in all rules that address the missing or defective Modbus slave,
preventing Modbus communications with the slave. However, it is important to emphasize again
that any change in the LMP-100 parameters stops data exchange while the the device is
reparameterized by the Profibus master.
The activation control in the control register is an option for situations where it is interesting
to the interrupt communications with a Modbus slave without reparameterization of the LMP-
100. The LMP-100 treats as disabled the Modbus rules that address a deactivated Modbus
slave. The rules remain disabled until slave reactivation is requested in the control register or
until the equipment is reparameterized. When reparameterized the rule enabled state is a
function solely of its “Enabled” parameter value.
Byte 0 must be set with the address of the Modbus slave that will have its activation state
changed. Byte 1 allows choosing if the slave will be activated or deactivated and also trigger the
activation change. The byte encoding is shown below.