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