--- a/modbus/mb_runtime.c Thu Jan 28 14:17:40 2021 +0000
+++ b/modbus/mb_runtime.c Thu Jan 28 14:50:26 2021 +0000
@@ -203,9 +203,11 @@
static int __read_inbits (void *mem_map, u16 start_addr, u16 bit_count, u8 *data_bytes) {
int res = __pack_bits(((server_mem_t *)mem_map)->ro_bits, start_addr, bit_count, data_bytes);
- /* update the counter of Modbus requests we have processed. */+ /* update the flag and counter of Modbus requests we have processed. */ ((server_mem_t *)mem_map)->flag_read_req_counter++;
+ ((server_mem_t *)mem_map)->flag_read_req_flag = 1; @@ -213,9 +215,11 @@
static int __read_outbits (void *mem_map, u16 start_addr, u16 bit_count, u8 *data_bytes) {
int res = __pack_bits(((server_mem_t *)mem_map)->rw_bits, start_addr, bit_count, data_bytes);
- /* update the counter of Modbus requests we have processed. */+ /* update the flag and counter of Modbus requests we have processed. */ ((server_mem_t *)mem_map)->flag_read_req_counter++;
+ ((server_mem_t *)mem_map)->flag_read_req_flag = 1; @@ -223,9 +227,11 @@
static int __write_outbits (void *mem_map, u16 start_addr, u16 bit_count, u8 *data_bytes) {
int res = __unpack_bits(((server_mem_t *)mem_map)->rw_bits, start_addr, bit_count, data_bytes);
- /* update the counter of Modbus requests we have processed. */+ /* update the flag and counter of Modbus requests we have processed. */ ((server_mem_t *)mem_map)->flag_write_req_counter++;
+ ((server_mem_t *)mem_map)->flag_write_req_flag = 1; @@ -238,8 +244,9 @@
if ((start_addr + word_count) > MEM_AREA_SIZE)
return -ERR_ILLEGAL_DATA_ADDRESS; /* ERR_ILLEGAL_DATA_ADDRESS defined in mb_util.h */
- /* update the counter of Modbus requests we have processed. */+ /* update the flag and counter of Modbus requests we have processed. */ ((server_mem_t *)mem_map)->flag_read_req_counter++;
+ ((server_mem_t *)mem_map)->flag_read_req_flag = 1; /* use memcpy() because loop with pointers (u16 *) caused alignment problems */
memcpy(/* dest */ (void *)data_words,
@@ -255,8 +262,9 @@
if ((start_addr + word_count) > MEM_AREA_SIZE)
return -ERR_ILLEGAL_DATA_ADDRESS; /* ERR_ILLEGAL_DATA_ADDRESS defined in mb_util.h */
- /* update the counter of Modbus requests we have processed. */+ /* update the flag and counter of Modbus requests we have processed. */ ((server_mem_t *)mem_map)->flag_read_req_counter++;
+ ((server_mem_t *)mem_map)->flag_read_req_flag = 1; /* use memcpy() because loop with pointers (u16 *) caused alignment problems */
memcpy(/* dest */ (void *)data_words,
@@ -273,8 +281,9 @@
if ((start_addr + word_count) > MEM_AREA_SIZE)
return -ERR_ILLEGAL_DATA_ADDRESS; /* ERR_ILLEGAL_DATA_ADDRESS defined in mb_util.h */
- /* update the counter of Modbus requests we have processed. */+ /* update the flag and counter of Modbus requests we have processed. */ ((server_mem_t *)mem_map)->flag_write_req_counter++;
+ ((server_mem_t *)mem_map)->flag_write_req_flag = 1; /* WARNING: The data returned in the data_words[] array is not guaranteed to be 16 bit aligned.
* It is not therefore safe to cast it to an u16 data type.
@@ -578,8 +587,10 @@
// -1 --> modbus node created!; no thread created
// >=0 --> modbus node created!; thread created!
server_nodes[index].mb_nd = -2;
+ server_nodes[index].mem_area.flag_write_req_flag = 0; server_nodes[index].mem_area.flag_write_req_counter = 0;
server_nodes[index].mem_area.flag_read_req_counter = 0;
+ server_nodes[index].mem_area.flag_read_req_flag = 0; /* see comment in mb_runtime.h to understad why we need to initialize these entries */
switch (server_nodes[index].node_address.naf) {
--- a/modbus/mb_runtime.h Thu Jan 28 14:17:40 2021 +0000
+++ b/modbus/mb_runtime.h Thu Jan 28 14:50:26 2021 +0000
@@ -42,14 +42,24 @@
u16 ro_words[MEM_AREA_SIZE];
u16 rw_words[MEM_AREA_SIZE];
/* Two flags to count the number of Modbus requests (read and write) we have
- * successfully received from any remote Modbus master- * These two flags will be mapped onto located variables+ * successfully received from any remote Modbus master. + * Two boolean flags that are set whenever we successfully process a + * Modbus request sent from a remote client. + * These flags will be mapped onto located variables * so the user's IEC 61131-3 code can check whether we are being
* polled by a Modbus master.
* The counters will roll over to 0 upon reaching maximum value.
+ * The user will probably periodically reset the boolean flags to false, + * and use this as a communication timeout + * (when it remains false in two consecutive periods) + * u8 for BOOL variable/flag + * u32 for UDINT variable/counter - u32 flag_write_req_counter;- u32 flag_read_req_counter;+ u8 flag_write_req_flag; + u32 flag_write_req_counter; + u32 flag_read_req_counter; --- a/modbus/modbus.py Thu Jan 28 14:17:40 2021 +0000
+++ b/modbus/modbus.py Thu Jan 28 14:50:26 2021 +0000
@@ -457,10 +457,10 @@
# execute the Modbus request.
# NOTE: If the Modbus slave has a 'current_location' of
- # then the "Modbus Read Request Counter" will be- # then the "Modbus Write Request Counter" will be+ # then the "Modbus Read Request Counter" will be %MD1.2.0 + # then the "Modbus Write Request Counter" will be %MD1.2.1 + # then the "Modbus Read Request Flag" will be %MD1.2.2 + # then the "Modbus Write Request Flag" will be %MD1.2.3 # Note that any MemoryArea contained under this server/slave
# will ocupy the locations of type
@@ -472,6 +472,8 @@
# and therefore never ocupy the locations
# used by the following flags/counters.
@@ -492,6 +494,24 @@
"location": "D" + ".".join([str(i) for i in current_location]) + ".1",
"description": "Modbus write request counter",
+ "name": "Modbus Read Request Flag", + "type": LOCATION_VAR_MEMORY, + "IEC_type": "BOOL", # BOOL flag + "var_name": "var_name", + "location": "X" + ".".join([str(i) for i in current_location]) + ".2", + "description": "Modbus read request flag", + "name": "Modbus write Request Flag", + "type": LOCATION_VAR_MEMORY, + "IEC_type": "BOOL", # BOOL flag + "var_name": "var_name", + "location": "X" + ".".join([str(i) for i in current_location]) + ".3", + "description": "Modbus write request flag", # recursively call all the Memory Areas under this Modbus server/save
# i.e., all the children objects which will be of class _MemoryAreaPlug
for child in self.IECSortedChildren():
@@ -697,10 +717,10 @@
# execute the Modbus request.
# NOTE: If the Modbus slave has a 'current_location' of
- # then the "Modbus Read Request Counter" will be- # then the "Modbus Write Request Counter" will be+ # then the "Modbus Read Request Counter" will be %MD1.2.0 + # then the "Modbus Write Request Counter" will be %MD1.2.1 + # then the "Modbus Read Request Flag" will be %MD1.2.2 + # then the "Modbus Write Request Flag" will be %MD1.2.3 # Note that any MemoryArea contained under this server/slave
# will ocupy the locations of type
@@ -712,6 +732,8 @@
# and therefore never ocupy the locations
# used by the following flags/counters.
@@ -732,6 +754,24 @@
"location": "D" + ".".join([str(i) for i in current_location]) + ".1",
"description": "Modbus write request counter",
+ "name": "Modbus Read Request Flag", + "type": LOCATION_VAR_MEMORY, + "IEC_type": "BOOL", # BOOL flag + "var_name": "var_name", + "location": "X" + ".".join([str(i) for i in current_location]) + ".2", + "description": "Modbus read request flag", + "name": "Modbus write Request Flag", + "type": LOCATION_VAR_MEMORY, + "IEC_type": "BOOL", # BOOL flag + "var_name": "var_name", + "location": "X" + ".".join([str(i) for i in current_location]) + ".3", + "description": "Modbus write request flag", # recursively call all the Memory Areas under this Modbus server/save
# i.e., all the children objects which will be of class _MemoryAreaPlug
for child in self.IECSortedChildren():
@@ -932,17 +972,11 @@
server_node_list.append(new_node)
- # We currently add 2 flags/counters to each Modbus server/slave+ # We currently add 4 flags/counters to each Modbus server/slave
- # We add the "Execution Control Flag" to each client request (one flag per request)- # to allow the user program to control when to execute the request (if not executed periodically)- # While all Modbus registers/coils are mapped onto a location- # with 4 numbers (e.g. %QX0.1.2.55), this control flag is mapped- # onto a location with 4 numbers (e.g. %QX0.1.2.0.0), where the last- # two numbers are always '0.0', and the first two identify the request.- # In the following if, we check for this condition by checking- # if there are at least 4 or more number in the location's address.+ # We add the Modbus read/write counter/flag to each Modbus slave/server + # to allow the user program to determine if the slave is being actively + # read from or written by by a remote Modbus client. for iecvar in child.GetLocations():
#print "child" + repr(iecvar)
if (len(iecvar["LOC"]) == 3) and (str(iecvar["NAME"]) not in loc_vars_list):
@@ -954,6 +988,14 @@
if iecvar["LOC"][2] == 1:
loc_vars.append("u32 *" + str(iecvar["NAME"]) + " = &server_nodes[%d].mem_area.flag_write_req_counter;" % (server_id))
loc_vars_list.append(str(iecvar["NAME"]))
+ # Add if it is a "Modbus Read Request Flag" (mapped onto %MDa.b.2), so last number is a '2' + if iecvar["LOC"][2] == 2: + loc_vars.append("u8 *" + str(iecvar["NAME"]) + " = &server_nodes[%d].mem_area.flag_read_req_flag;" % (server_id)) + loc_vars_list.append(str(iecvar["NAME"])) + # Add if it is a "Modbus Write Request Counter" (mapped onto %MDa.b.3), so last number is a '3' + if iecvar["LOC"][2] == 3: + loc_vars.append("u8 *" + str(iecvar["NAME"]) + " = &server_nodes[%d].mem_area.flag_write_req_flag;" % (server_id)) + loc_vars_list.append(str(iecvar["NAME"])) for subchild in child.IECSortedChildren():
new_memarea = GetTCPServerMemAreaPrinted(self, subchild, nodeid)
@@ -983,7 +1025,31 @@
server_node_list.append(new_node)
+ # We currently add 4 flags/counters to each Modbus server/slave + # We add the Modbus read/write counter/flag to each Modbus slave/server + # to allow the user program to determine if the slave is being actively + # read from or written by by a remote Modbus client. + for iecvar in child.GetLocations(): + #print "child" + repr(iecvar) + if (len(iecvar["LOC"]) == 3) and (str(iecvar["NAME"]) not in loc_vars_list): + # Add if it is a "Modbus Read Request Counter" (mapped onto %MDa.b.0), so last number is a '0' + if iecvar["LOC"][2] == 0: + loc_vars.append("u32 *" + str(iecvar["NAME"]) + " = &server_nodes[%d].mem_area.flag_read_req_counter;" % (server_id)) + loc_vars_list.append(str(iecvar["NAME"])) + # Add if it is a "Modbus Write Request Counter" (mapped onto %MDa.b.1), so last number is a '1' + if iecvar["LOC"][2] == 1: + loc_vars.append("u32 *" + str(iecvar["NAME"]) + " = &server_nodes[%d].mem_area.flag_write_req_counter;" % (server_id)) + loc_vars_list.append(str(iecvar["NAME"])) + # Add if it is a "Modbus Read Request Flag" (mapped onto %MDa.b.2), so last number is a '2' + if iecvar["LOC"][2] == 2: + loc_vars.append("u8 *" + str(iecvar["NAME"]) + " = &server_nodes[%d].mem_area.flag_read_req_flag;" % (server_id)) + loc_vars_list.append(str(iecvar["NAME"])) + # Add if it is a "Modbus Write Request Counter" (mapped onto %MDa.b.3), so last number is a '3' + if iecvar["LOC"][2] == 3: + loc_vars.append("u8 *" + str(iecvar["NAME"]) + " = &server_nodes[%d].mem_area.flag_write_req_flag;" % (server_id)) + loc_vars_list.append(str(iecvar["NAME"])) for subchild in child.IECSortedChildren():
new_memarea = GetTCPServerMemAreaPrinted(
