report hardware version to STDERR

diff --git a/lib/RFID/Serial/3M810.pm b/lib/RFID/Serial/3M810.pm
index 9b6b618..c7144fa 100644 (file)
--- a/lib/RFID/Serial/3M810.pm
+++ b/lib/RFID/Serial/3M810.pm
@@ -97,7 +97,7 @@ cmd(
        my $data = shift;
        my $rest = assert $data => '04 00 11';
        my $hw_ver = join('.', unpack('CCCC', $rest));
-       print "hardware version $hw_ver\n";
+       warn "# 3M 810 hardware version $hw_ver\n";
 });
 
 cmd(