Flintec LDU 68.2 - Manual (Page 21)

LDU 68.1 & 68.2 Technical Manual, Rev. 12 January 2010 Page 21 of 28
8.8. Commands for External I/O Control – IN, IO, IM
The LDU 68.1 has 2 independent logic inputs and 2 independent logic outputs. These inputs and outputs can
be configured and controlled completely via the LDU. The logic inputs can be read directly by the host
application and the logic outputs can be fully controlled via the setpoint commands.
The following group of commands allows the status of the 2 logic inputs to be read, the status of the 2 logic
outputs to read or modified and to configure the logic outputs for internal or external control.
The use of the setpoint commands (Sn, Hn, An) are explained in the following chapter 8.9.
8.8.1. IN Read the Status of the Input Channels
This command reads the status of the two logic inputs.
Master (PC / SPS) sends Slave (LDU XX.X) responds Meaning
IN  IN:0001 Request: Input 0 is active
IN  IN:0010 Request: Input 1 is active
IN  IN:0011 Request: Inputs 0 and 1 are active
The status response is in the form of a four digit code where 0 = false and 1 = true (inputs are active “high”), the
least significant bit corresponding to Input 0 etc.
8.8.2. IO Read / Set the Status of the Output Channels
This command reads and can modify the status of the two logic outputs (if enabled by the IM command).
Master (PC / SPS) sends Slave (LDU XX.X) responds Meaning
IO
 IO:0001 Request: Output 0 is active
IO
 IO:0010 Request: Output 1 is active
IO  IO:0011 Request: Outputs 0 and 1 are active
IO 0001  OK Setup: Output 0 is active
IO 0010
 OK Setup: Output 1 is active
IO 0011
 OK Setup: Outputs 0 and 1 are active
The status response is in the form of a four digit code where 0 = false and 1 = true (outputs are normally open,
open drain MOSFETs), the least significant bit corresponding to Output 0 etc.
The status of the outputs can be changed by issuing the IO command with the appropriate 4 digit code e.g. IO
0001 where in this example output 0 will be activated (FET conducting). Please note that the status of the logic
outputs is normally determined by the internal setpoints (see chapter 8.10) and therefore setting the logic
output status using the IO commands is not allowed.
However, the IM command can be used to allow the status of the logic outputs to be set via the IO command or
set their status directly by the host application. Factory default: IO=0000
8.8.3. IM Control of the logic outputs by the host application
The logic outputs can be controlled by the host application (as opposed to the normal internal setpoints) if they
are enabled by the IM command and the appropriate 4 digit code.
Master (PC / SPS) sends Slave (LDU XX.X) responds Meaning
IM  IM:0001 Request: Output 0 enabled
IM  IM:0010 Request: Output 1 enabled
IM  IM:0011 Request: Outputs 0 and 1 enabled
IM 0001
 OK Setup: Output 0 enabled
IM 0010
 OK Einstellung: Output 1 enabled
IM 0011  OK Einstellung: Outputs 0 and 1 enabled
IM 0000  OK Einstellung: Both outputs disabled
A “1” bit in the code enables the corresponding logic output to be controlled by the host application using the IO
command. A “0” in the code leaves the corresponding logic output controlled by the internal setpoint. Logic
output 0 is again the least significant bit.
Note:
When reading the status of the logic outputs using the IO command, the setpoint status will be returned
regardless of the IM setting. Sending IM 0000 disables the external logic output control.
Factory default: IM=0000