From a00ab52931a587cf29c53a945e9295b4d7fe41ba Mon Sep 17 00:00:00 2001
From: Daniel Golle <daniel@makrotopia.org>
Date: Thu, 28 Mar 2019 01:52:04 +0100
Subject: [PATCH] Add support for RS485 to modbus plugin
Allow setting up RS485 mode for Modbus-RTU
---
src/collectd.conf.pod | 6 +++++
src/modbus.c | 55 +++++++++++++++++++++++++++++++++++++++----
2 files changed, 57 insertions(+), 4 deletions(-)
--- a/src/collectd.conf.pod
+++ b/src/collectd.conf.pod
@@ -4234,6 +4234,12 @@ For Modbus/RTU, specifies the path to th
For Modbus/RTU, specifies the baud rate of the serial device.
Note, connections currently support only 8/N/1.
+=item B<UARTType> I<UARTType>
+
+For Modbus/RTU, specifies the type of the serial device.
+RS232, RS422 and RS485 are supported. Defaults to RS232.
+Available only on Linux systems with libmodbus>=2.9.4.
+
=item B<Interval> I<Interval>
Sets the interval (in seconds) in which the values will be collected from this
--- a/src/modbus.c
+++ b/src/modbus.c
@@ -95,6 +95,12 @@ enum mb_conntype_e /* {{{ */
MBCONN_RTU }; /* }}} */
typedef enum mb_conntype_e mb_conntype_t;
+enum mb_uarttype_e /* {{{ */
+{ UARTTYPE_RS232,
+ UARTTYPE_RS422,
+ UARTTYPE_RS485 }; /* }}} */
+typedef enum mb_uarttype_e mb_uarttype_t;
+
struct mb_data_s;
typedef struct mb_data_s mb_data_t;
struct mb_data_s /* {{{ */
@@ -124,8 +130,9 @@ struct mb_host_s /* {{{ */
char host[DATA_MAX_NAME_LEN];
char node[NI_MAXHOST]; /* TCP hostname or RTU serial device */
/* char service[NI_MAXSERV]; */
- int port; /* for Modbus/TCP */
- int baudrate; /* for Modbus/RTU */
+ int port; /* for Modbus/TCP */
+ int baudrate; /* for Modbus/RTU */
+ mb_uarttype_t uarttype; /* UART type for Modbus/RTU */
mb_conntype_t conntype;
cdtime_t interval;
@@ -390,6 +397,22 @@ static int mb_init_connection(mb_host_t
return status;
}
+#if defined(linux) && LIBMODBUS_VERSION_CHECK(2, 9, 4)
+ switch (host->uarttype) {
+ case UARTTYPE_RS485:
+ if (modbus_rtu_set_serial_mode(host->connection, MODBUS_RTU_RS485))
+ DEBUG("Modbus plugin: Setting RS485 mode failed.");
+ break;
+ case UARTTYPE_RS422:
+ /* libmodbus doesn't say anything about full-duplex symmetric RS422 UART */
+ break;
+ case UARTTYPE_RS232:
+ break;
+ default:
+ DEBUG("Modbus plugin: Invalid UART type!.");
+ }
+#endif /* defined(linux) && LIBMODBUS_VERSION_CHECK(2, 9, 4) */
+
return 0;
} /* }}} int mb_init_connection */
#endif /* !LEGACY_LIBMODBUS */
@@ -951,11 +974,35 @@ static int mb_config_add_host(oconfig_it
status = -1;
} else if (strcasecmp("Device", child->key) == 0) {
status = cf_util_get_string_buffer(child, host->node, sizeof(host->node));
- if (status == 0)
+ if (status == 0) {
host->conntype = MBCONN_RTU;
+ host->uarttype = UARTTYPE_RS232;
+ }
} else if (strcasecmp("Baudrate", child->key) == 0)
status = cf_util_get_int(child, &host->baudrate);
- else if (strcasecmp("Interval", child->key) == 0)
+ else if (strcasecmp("UARTType", child->key) == 0) {
+#if defined(linux) && !LEGACY_LIBMODBUS && LIBMODBUS_VERSION_CHECK(2, 9, 4)
+ char buffer[NI_MAXHOST];
+ status = cf_util_get_string_buffer(child, buffer, sizeof(buffer));
+ if (status != 0)
+ break;
+ if (strncmp(buffer, "RS485", 6) == 0)
+ host->uarttype = UARTTYPE_RS485;
+ else if (strncmp(buffer, "RS422", 6) == 0)
+ host->uarttype = UARTTYPE_RS422;
+ else if (strncmp(buffer, "RS232", 6) == 0)
+ host->uarttype = UARTTYPE_RS232;
+ else {
+ ERROR("Modbus plugin: The UARTType \"%s\" is unknown.", buffer);
+ status = -1;
+ break;
+ }
+#else
+ ERROR("Modbus plugin: Option `UARTType' not supported. Please "
+ "upgrade libmodbus to at least 2.9.4");
+ return -1;
+#endif
+ } else if (strcasecmp("Interval", child->key) == 0)
status = cf_util_get_cdtime(child, &host->interval);
else if (strcasecmp("Slave", child->key) == 0)
/* Don't set status: Gracefully continue if a slave fails. */