I haven't been following this thread but I found a couple of bugs in
modbus.c some time back. I don't know if they are the same problems
Victor found.
Here is the patch for modbus.c:
From ebaefba238af22e4f30febc61175c7f9d3211cb4 Mon Sep 17 00:00:00 2001
From: Les Newell <les.new...@fastmail.co.uk>
Date: Mon, 13 Aug 2012 11:15:19 +0100
Subject: [PATCH] A number of bug fixes for modbus:
Not calculating packet size for function code 2 (Read discrete inputs)
sending incorrect data when forcing multiple coils using more than one byte.
---
src/hal/user_comps/modbus.c | 5 +++--
1 files changed, 3 insertions(+), 2 deletions(-)
diff --git a/src/hal/user_comps/modbus.c b/src/hal/user_comps/modbus.c
index ed213c2..fe9cf37 100644
--- a/src/hal/user_comps/modbus.c
+++ b/src/hal/user_comps/modbus.c
@@ -151,7 +151,8 @@ static unsigned int
compute_response_size(modbus_param_t *mb_param,
offset = mb_param->header_length;
switch (query[offset + 1]) {
- case 0x01: {
+ case 0x01:
+ case 0x02: {
/* Header + nb values (code from force_multiple_coils) */
int coil_count = (query[offset + 4] << 8) | query[offset + 5];
response_size_computed = 3 +
@@ -784,6 +785,7 @@ int force_multiple_coils(modbus_param_t *mb_param,
int slave,
int coil_check = 0;
int status;
int query_ret;
+ int pos = 0;
unsigned char query[MAX_PACKET_SIZE];
@@ -800,7 +802,6 @@ int force_multiple_coils(modbus_param_t *mb_param,
int slave,
for (i = 0; i < byte_count; i++) {
int bit;
- int pos = 0;
bit = 0x01;
query[query_size] = 0;
--
1.5.4.3
By the way, did anyone try the Modbus module I posted on the list a
while back? <http://www.shootspammers.org.uk/modbus.zip>. It is a
multi-threaded module that can handle any number of modbus clients on
any number of ports (serial or Ethernet). It can create HAL pins for
coils, inputs, holding registers and input registers. Registers can be
either integers or floating point with scaling and offsetting. It has
been tested fairly thoroughly on serial but I haven't tested Ethernet.
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