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27
I/O Sentinel
®
4 Installation and Operation Manual
APPENDIX
Message structure via external control computer:
The IO Sentinel supports the monitoring and control of relays and status inputs via UDP
messages. Under Email/Network Setup “Enable Extension” must be enabled and the
Extension Port set. The Extension IP address must also be set to whatever IP address mes-
sages will be accepted from.
Relays can be turned on or off by sending a UDP packet to the device on the Extension Port
using the following structure:
typedef struct
{
BYTE Magic;
BYTE RelayNumber;
BYTE State;
BYTE CS;
}UDP_MSG;
Magic should be set to 0x8B.
RelayNumber should be 0-3 for Relays 1-4.
State should be 0 for OFF and 1 for ON
CS should be calculated as Magic+RelaState
No reply is sent from the device after receiving this message; it is up to the calling applica-
tion to make a query to ensure that the relay was set correctly.
Relays and Status Inputs can be queried as well. The following structure is used similar to
the one above for setting a relay’s state.
typedef struct
{
BYTE Magic;
BYTE RelayState[4];
BYTE StatusState[4];
BYTE CS;
}UDP_QUERY;
When querying the device’s state you must send a UDP_MSG packet with the Magic set to
0x72, a UDP_QUERY packet is then returned. Send this packet on the Extension Port and
the device will return a same sized packet containing the following information on the same
port.
Magic should be set to 0x72
RelayState is an array of the 4 relay states with 0 being OFF and 1 being ON.
StatusState is an array of the 4 input status states with 0 being OFF and 1 being ON
CS = sum of the rest of the packet.
A Unicast packet is sent to the Extension IP address on the Extension Port.
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