--- a/modbus/modbus.py Mon Dec 21 22:32:03 2020 +0000
+++ b/modbus/modbus.py Fri Dec 25 17:11:38 2020 +0000
@@ -146,7 +146,7 @@
"IEC_type": "BYTE", # BYTE flag
"var_name": "var_name",
"location": "B" + ".".join([str(i) for i in current_location]) + ".0.1",
- "description": "Modbus request status flag",
+ "description": "Modbus request status flag (0 -> OK, 1 -> Network error, 2 -> Received invalid frame, 3 -> Timeout, 4 -> Received error frame)",
"children": []})
entries.append({
"name": "Modbus Error Code",
@@ -188,6 +188,7 @@
return [], "", False
+
#
#
#
@@ -883,17 +884,17 @@
# test if the located variable
# (a) has relative address in request specified range
# AND is NOT
- # (b) is a control flag added by this modbus plugin
- # to control its execution at runtime.
- # Currently, we only add the "Execution Control Flag"
- # to each client request (one flag per request)
- # to control when to execute the request (if not executed periodically)
+ # (b) is a flag added by this modbus plugin.
+ # We currently add 3 flags: An execution control flag
+ # and another two status flags.
+ # 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 their are at least 4 or more number in the location's address.
+ # if there are at least 4 or more number in the location's address.
if ( relative_addr in xrange(int(GetCTVal(subchild, 2))) # condition (a) explained above
and len(iecvar["LOC"]) < 5): # condition (b) explained above
if str(iecvar["NAME"]) not in loc_vars_list:
@@ -907,10 +908,18 @@
loc_vars.append("u8 *" + str(iecvar["NAME"]) + " = &client_requests[%d].flag_exec_req;" % (client_requestid))
loc_vars_list.append(str(iecvar["NAME"]))
# Add if it is a "Modbus Request Status flag" (mapped onto %QWa.b.c.0.1), so last number is a '1'
+ # -> will store the result of the last executed MB transaction
+ # 1 -> error accessing IP network, or serial interface
+ # 2 -> reply received from server was an invalid frame
+ # 3 -> server did not reply before timeout expired
+ # 4 -> server returned a valid Modbus error frame
+ # -> will be reset (set to 0) once this MB transaction has completed sucesfully
if iecvar["LOC"][4] == 1:
loc_vars.append("u8 *" + str(iecvar["NAME"]) + " = &client_requests[%d].flag_tn_error_code;" % (client_requestid))
loc_vars_list.append(str(iecvar["NAME"]))
# Add if it is a "Modbus Error code" (mapped onto %QWa.b.c.0.2), so last number is a '2'
+ # -> if "Modbus Request Status flag" is 4, this flag will store the MB error code returned by the MB server in a MB error frame
+ # -> will be reset (set to 0) once this MB transaction has completed succesfully
if iecvar["LOC"][4] == 2:
loc_vars.append("u8 *" + str(iecvar["NAME"]) + " = &client_requests[%d].flag_mb_error_code;" % (client_requestid))
loc_vars_list.append(str(iecvar["NAME"]))
@@ -936,11 +945,11 @@
# test if the located variable
# (a) has relative address in request specified range
# AND is NOT
- # (b) is a control flag added by this modbus plugin
- # to control its execution at runtime.
- # Currently, we only add the "Execution Control Flag"
- # to each client request (one flag per request)
- # to control when to execute the request (if not executed periodically)
+ # (b) is a flag added by this modbus plugin.
+ # We currently add 3 flags: An execution control flag
+ # and another two status flags.
+ # 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
@@ -961,10 +970,18 @@
loc_vars.append("u8 *" + str(iecvar["NAME"]) + " = &client_requests[%d].flag_exec_req;" % (client_requestid))
loc_vars_list.append(str(iecvar["NAME"]))
# Add if it is a "Modbus Request Status flag" (mapped onto %QWa.b.c.0.1), so last number is a '1'
+ # -> will store the result of the last executed MB transaction
+ # 1 -> error accessing IP network, or serial interface
+ # 2 -> reply received from server was an invalid frame
+ # 3 -> server did not reply before timeout expired
+ # 4 -> server returned a valid Modbus error frame
+ # -> will be reset (set to 0) once this MB transaction has completed sucesfully
if iecvar["LOC"][4] == 1:
loc_vars.append("u8 *" + str(iecvar["NAME"]) + " = &client_requests[%d].flag_tn_error_code;" % (client_requestid))
loc_vars_list.append(str(iecvar["NAME"]))
# Add if it is a "Modbus Error code" (mapped onto %QWa.b.c.0.2), so last number is a '2'
+ # -> if "Modbus Request Status flag" is 4, this flag will store the MB error code returned by the MB server in a MB error frame
+ # -> will be reset (set to 0) once this MB transaction has completed succesfully
if iecvar["LOC"][4] == 2:
loc_vars.append("u8 *" + str(iecvar["NAME"]) + " = &client_requests[%d].flag_mb_error_code;" % (client_requestid))
loc_vars_list.append(str(iecvar["NAME"]))