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--- ha:sr201 [13/06/2025 22:06] – andrew
+++ ha:sr201 [16/06/2025 23:15] (current) – [Testing from BASH] andrew
@@ Line 29: / Line 29: @@
 Below is a quick play about from BASH to test the relay with raw TCP.  ''nc'' is Netcat, a really useful utility to communicate with raw TCP/IP, either to send packets as here, but also you can use it to set up a listener on a port. See the repo link above to work out the data fed to nc from the printf. Using printf as echo by default sends a newline / CR which will upset the module.
 If you're stuck on windows you probably don't have netcat, yet another reason to upgrade to Linux.
+<code>
+#    Commands are ASCII strings that must be sent in one packet
+#    (even for TCP):
+#
+#        0R     No operation (but return status).
+#
+#        1R*    Close relay if it's open, wait approx 1/2 a second, open
+#               relay.
+#
+#        1R     Close relay if it's open.
+#
+#        1R:0   Close relay if it's open.
+#
+#        1R:n   Close relay if it's open, then in n seconds (1 <= n <= 65535)
+#               open it.
+#
+#        2R     Open relay if it's closed.
+#
+#    Where:
+#
+#        R      is the relay number, '1' .. '8'.  The main board has relay's
+#               '1' and '2', the extension board (if present) has the rest.
+#               If R is 'X' all relays are effected.
+#
+#    If the command is sent over TCP (not UDP, TCP only), the relay will
+#    reply with a string of 8 0's and 1's, representing the "before" command
+#    was executed" state of relay's 1..8 in that order.  A '0' is sent if the
+#    relay is open, '1' if closed.
+</code>
 <code>