comm_moninj: set keepalive for socket (#1843)

artiq/coredevice/comm_moninj.py

@@ -2,7 +2,7 @@ import asyncio
 import logging
 import struct
 from enum import Enum
-
+from .comm import set_keepalive
 
 __all__ = ["TTLProbe", "TTLOverride", "CommMonInj"]
 
@@ -29,6 +29,8 @@ class CommMonInj:
 
     async def connect(self, host, port=1383):
         self._reader, self._writer = await asyncio.open_connection(host, port)
+        set_keepalive(self._writer.transport.get_extra_info('socket'), 1, 1, 3)
+
         try:
             self._writer.write(b"ARTIQ moninj\n")
             # get device endian