From ea9fe134a242ddd0ea1df9e1c4aa4ddea1542ff6 Mon Sep 17 00:00:00 2001
From: Tom Keffer <tkeffer@gmail.com>
Date: Sat, 15 Sep 2018 05:48:46 -0700
Subject: [PATCH] Guard against a negative value for 'interval' in WMR200
 stations.

---
 bin/weewx/drivers/wmr200.py | 7 ++++++-
 docs/changes.txt            | 2 ++
 2 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/bin/weewx/drivers/wmr200.py b/bin/weewx/drivers/wmr200.py
index 24183f55..b0046c3d 100644
--- a/bin/weewx/drivers/wmr200.py
+++ b/bin/weewx/drivers/wmr200.py
@@ -1943,7 +1943,12 @@ class WMR200(weewx.drivers.AbstractDevice):
                 timestamp_packet_interval = timestamp_packet_current \
                         - timestamp_packet_previous
 
-                if pkt.timestamp_record() > (timestamp_packet_previous
+                if timestamp_packet_interval < 0:
+                    loginf(('genStartup() Discarding received archive record that presented out-of-order; '
+                            'current timestamp:%s; previous timestamp:%s')
+                           % (weeutil.weeutil.timestamp_to_string(timestamp_packet_current),
+                              weeutil.weeutil.timestamp_to_string(timestamp_packet_previous)))
+                elif pkt.timestamp_record() > (timestamp_packet_previous
                                              + self._archive_threshold):
                     loginf(('genStartup() Discarding received archive'
                             ' record exceeding archive interval cnt:%d'
diff --git a/docs/changes.txt b/docs/changes.txt
index f63d3941..cc7bf50d 100644
--- a/docs/changes.txt
+++ b/docs/changes.txt
@@ -29,6 +29,8 @@ doing a merge to the new config file. Fixes issue #217.
 Example xstats now includes tags for last_year and last_year_todate.
 Thanks to user evilbunny2008. PR #325.
 
+Guard against a negative value for 'interval' in WMR200 stations.
+
 
 3.8.2 08/15/2018