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43 lines
1.6 KiB
43 lines
1.6 KiB
From 1c5d969f46ccd5333f602dfbe2b0a1295650b9b0 Mon Sep 17 00:00:00 2001
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From: =?UTF-8?q?St=C3=A9phane=20Raimbault?= <stephane.raimbault@gmail.com>
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Date: Wed, 25 Oct 2017 20:35:47 +0200
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Subject: [PATCH 1/2] Only set SER_RS485_ENABLED bit of existing RS485 settings
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Thanks to @JCWren
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---
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src/modbus-rtu.c | 10 +++++++++-
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1 file changed, 9 insertions(+), 1 deletion(-)
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diff --git a/src/modbus-rtu.c b/src/modbus-rtu.c
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index 8d9f386..f2911d6 100644
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--- a/src/modbus-rtu.c
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+++ b/src/modbus-rtu.c
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@@ -909,9 +909,13 @@ int modbus_rtu_set_serial_mode(modbus_t *ctx, int mode)
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#if HAVE_DECL_TIOCSRS485
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modbus_rtu_t *ctx_rtu = ctx->backend_data;
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struct serial_rs485 rs485conf;
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- memset(&rs485conf, 0x0, sizeof(struct serial_rs485));
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if (mode == MODBUS_RTU_RS485) {
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+ // Get
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+ if (ioctl(ctx->s, TIOCGRS485, &rs485conf) < 0) {
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+ return -1;
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+ }
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+ // Set
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rs485conf.flags = SER_RS485_ENABLED;
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if (ioctl(ctx->s, TIOCSRS485, &rs485conf) < 0) {
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return -1;
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@@ -923,6 +927,10 @@ int modbus_rtu_set_serial_mode(modbus_t *ctx, int mode)
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/* Turn off RS485 mode only if required */
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if (ctx_rtu->serial_mode == MODBUS_RTU_RS485) {
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/* The ioctl call is avoided because it can fail on some RS232 ports */
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+ if (ioctl(ctx->s, TIOCGRS485, &rs485conf) < 0) {
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+ return -1;
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+ }
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+ rs485conf.flags &= ~SER_RS485_ENABLED;
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if (ioctl(ctx->s, TIOCSRS485, &rs485conf) < 0) {
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return -1;
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}
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--
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2.21.0
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