Allow an IF response to TX/RX for kenwood.c

https://github.com/Hamlib/Hamlib/issues/229

rigs/kenwood/kenwood.c

@@ -343,8 +343,8 @@ transaction_write:
     }
 
 transaction_read:
-    /* allow one extra byte for terminator we don't return */
+    /* allow room for most any response */
-    len = min(datasize ? datasize + 1 : strlen(priv->verify_cmd) + 13,
+    len = min(datasize ? datasize + 1 : strlen(priv->verify_cmd) + 32,
               KENWOOD_MAX_BUF_LEN);
     retval = read_string(&rs->rigport, buffer, len, cmdtrm, strlen(cmdtrm));
     rig_debug(RIG_DEBUG_TRACE, "%s: read_string(len=%d)='%s'\n", __func__,
@@ -491,6 +491,15 @@ transaction_read:
                   __func__,
                   priv->verify_cmd, buffer);
 
+        // seems some rigs will send back an IF response to RX/TX when it changes the status
+        // normally RX/TX returns nothing when it's a null effect
+        // TS-950SDX is known to behave this way
+        if (strncmp(cmdstr,"RX",2)==0 || strncmp(cmdstr,"TX",2)==0) {
+            if (strncmp(priv->verify_cmd,"IF",2)==0) {
+                rig_debug(RIG_DEBUG_TRACE,"%s: RX/TX got IF response so we're good\n", __func__);
+                goto transaction_quit;
+            }
+        }
         if (priv->verify_cmd[0] != buffer[0]
                 || (priv->verify_cmd[1] && priv->verify_cmd[1] != buffer[1]))
         {

rigs/kenwood/kenwood.h

@@ -27,7 +27,7 @@
 #include <string.h>
 #include "token.h"
 
-#define BACKEND_VER "20200427"
+#define BACKEND_VER "20200428"
 
 #define EOM_KEN ';'
 #define EOM_TH '\r'